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Showing papers in "ACS energy letters in 2018"


Journal ArticleDOI
TL;DR: In this paper, a review of recent advances in rechargeable aqueous zinc-ion batteries (ZIBs) is presented, highlighting the design of a highly reversible Zn anode, optimization of the electrolyte, and a wide range of cathode materials and their energy storage mechanisms.
Abstract: Although current high-energy-density lithium-ion batteries (LIBs) have taken over the commercial rechargeable battery market, increasing concerns about limited lithium resources, high cost, and insecurity of organic electrolyte scale-up limit their further development. Rechargeable aqueous zinc-ion batteries (ZIBs), an alternative battery chemistry, have paved the way not only for realizing environmentally benign and safe energy storage devices but also for reducing the manufacturing costs of next-generation batteries. This Review underscores recent advances in aqueous ZIBs; these include the design of a highly reversible Zn anode, optimization of the electrolyte, and a wide range of cathode materials and their energy storage mechanisms. We also present recent advanced techniques that aim at overcoming the current issues in aqueous ZIB systems. This Review on the future perspectives and research directions will provide a guide for future aqueous ZIB study.

1,370 citations


Journal ArticleDOI
TL;DR: Aqueous Zn-V2O5 battery chemistry is reported in this paper, which employs commercial V2O-5 cathode, Zn anode, and 3 M Zn(CF3SO3)2 electrolyte.
Abstract: We report an aqueous Zn–V2O5 battery chemistry employing commercial V2O5 cathode, Zn anode, and 3 M Zn(CF3SO3)2 electrolyte. We elucidate the Zn-storage mechanism in the V2O5 cathode to be that hydrated Zn2+ can reversibly (de)intercalate through the layered structure. The function of the co-intercalated H2O is revealed to be shielding the electrostatic interactions between Zn2+ and the host framework, accounting for the enhanced kinetics. In addition, the pristine bulk V2O5 gradually evolves into porous nanosheets upon cycling, providing more active sites for Zn2+ storage and thus rendering an initial capacity increase. As a consequence, a reversible capacity of 470 mAh g–1 at 0.2 A g–1 and a long-term cyclability with 91.1% capacity rentention over 4000 cycles at 5 A g–1 are achieved. The combination of the good battery performance, safety, scalable materials synthesis, and facile cell assembly indicates this aqueous Zn–V2O5 system is promising for stationary grid storage applications.

675 citations


Journal ArticleDOI
TL;DR: In this article, the challenges and recent developments related to rechargeable zinc-ion battery research are presented, as well as recent research trends and directions on electrode materials that can store Zn2+ and electrolytes that can improve the battery performance.
Abstract: The zinc-ion battery (ZIB) is a 2 century-old technology but has recently attracted renewed interest owing to the possibility of switching from primary to rechargeable ZIBs. Nowadays, ZIBs employing a mild aqueous electrolyte are considered one of the most promising candidates for emerging energy storage systems (ESS) and portable electronics applications due to their environmental friendliness, safety, low cost, and acceptable energy density. However, there are many drawbacks associated with these batteries that have not yet been resolved. In this Review, we present the challenges and recent developments related to rechargeable ZIB research. Recent research trends and directions on electrode materials that can store Zn2+ and electrolytes that can improve the battery performance are comprehensively discussed.

612 citations


Journal ArticleDOI
TL;DR: A new ligand capping strategy utilizing common and inexpensive long-chain zwitterionic molecules such as 3-(N,N-dimethyloctadecylammonio)propanesulfonate is proposed, resulting in much improved chemical durability and allows for the isolation of clean NCs with high photoluminescence quantum yields of above 90% after four rounds of precipitation/redispersion.
Abstract: Colloidal lead halide perovskite nanocrystals (NCs) have recently emerged as versatile photonic sources. Their processing and optoelectronic applications are hampered by the loss of colloidal stability and structural integrity due to the facile desorption of surface capping molecules during isolation and purification. To address this issue, herein, we propose a new ligand capping strategy utilizing common and inexpensive long-chain zwitterionic molecules such as 3-(N,N-dimethyloctadecylammonio)propanesulfonate, resulting in much improved chemical durability. In particular, this class of ligands allows for the isolation of clean NCs with high photoluminescence quantum yields (PL QYs) of above 90% after four rounds of precipitation/redispersion along with much higher overall reaction yields of uniform and colloidal dispersible NCs. Densely packed films of these NCs exhibit high PL QY values and effective charge transport. Consequently, they exhibit photoconductivity and low thresholds for amplified spontane...

572 citations


Journal ArticleDOI
TL;DR: In this article, a review of 2D supercapacitor electrode materials including transition metal dichalcogenides, transition metal oxides and hydroxides, MXenes, and phosphorene is presented.
Abstract: Supercapacitors represent a major technology to store energy for many applications including electronics, automobiles, military, and space. Despite their high power density, the energy density in supercapacitors is presently inferior to that of the state-of-the-art Li-ion batteries owing to the limited electrochemical performance exhibited by the conventional electrode materials. The advent of two-dimensional (2D) nanomaterials has spurred enormous research interest as supercapacitor electrode materials due to their fascinating electrochemical and mechanical properties. This Review discusses cutting-edge research on some of the key 2D supercapacitor electrode materials including transition metal dichalcogenides, transition metal oxides and hydroxides, MXenes, and phosphorene. Various synthetic approaches, novel electrode designs, and microstructure tuning of these 2D materials for achieving high energy and power densities are discussed.

561 citations


Journal ArticleDOI
TL;DR: In this paper, a layered Mg2+-intercalated V2O5 was used as the cathode material for aqueous ZIBs, achieving high capacity of 353 and 264 mA h g-1 at current densities of 100 and 1000 mA g -1, respectively.
Abstract: The performance of chemically intercalated V2O5 was found to strongly depend on the interlayer spacing, which is related to the radius of hydrated metal ion, which can be readily tuned by using different intercalated metals. We report a layered Mg2+-intercalated V2O5 as the cathode material for aqueous ZIBs. The large radius of hydrated Mg2+ (∼4.3 A, compared with 3.8 A of commonly used Li+) results in an interlayer spacing as large as 13.4 A (against 11.07 A for Li+-intercalated V2O5), which allows efficient Zn2+ (de)insertion. As a result, the obtained porous Mg0.34V2O5·0.84H2O cathodes work in a wide potential window of 0.1 to 1.8 V versus Zn2+/Zn, and can deliver high capacities of 353 and 264 mA h g–1 at current densities of 100 and 1000 mA g–1, respectively, along with long-term durability. Furthermore, the reversible Zn2+ (de)intercalation reaction mechanism is confirmed by multiple characterizations methods.

516 citations


Journal ArticleDOI
TL;DR: In this paper, a perspective on the most exciting developments in the low-dimensional organometal halide perovskites is presented, which are significantly different from those of 3D and 2D structures.
Abstract: Organometal halide perovskites have recently emerged as a highly promising class of functional materials for a variety of applications. The exceptional structural tunability enables these materials to possess three- (3D), two- (2D), one- (1D), and zero-dimensional (0D) structures at the molecular level. Remarkable progress has been realized in the research of perovskites in recent years, focusing mainly on 3D and 2D structures but leaving low-dimensional 1D and 0D structures significantly underexplored. Here we offer our perspective on the most exciting developments in the low-dimensional organometal halide perovskites. Due to the strong quantum confinement and site isolation, 1D and 0D perovskites exhibit remarkable and useful properties that are significantly different from those of 3D and 2D perovskites. The excitement about the recent developments lies not only in the specific achievements but also in what these materials represent in terms of a new paradigm in materials design.

462 citations


Journal ArticleDOI
TL;DR: In this paper, a pyridinic-N-dominated doped graphene with abundant vacancy defects was constructed and the optimized sample with an ultrahigh pore volume (3.43 cm3 g-1) exhibits unprecedented ORR activity with a half-wave potential of 0.28 V for ORR and 0.85 V in alkaline.
Abstract: Identification of catalytic sites for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in carbon materials remains a great challenge. Here, we construct a pyridinic-N-dominated doped graphene with abundant vacancy defects. The optimized sample with an ultrahigh pore volume (3.43 cm3 g–1) exhibits unprecedented ORR activity with a half-wave potential of 0.85 V in alkaline. For the first time, density functional theory results indicate that the quadri-pyridinic N-doped carbon site synergized with a vacancy defect is the active site, which presents the lowest overpotential of 0.28 V for ORR and 0.28 V for OER. The primary Zn–air batteries display a maximum power density of 115.2 mW cm–2 and an energy density as high as 872.3 Wh kg–1. The rechargeable Zn–air batteries illustrate a low discharge–charge overpotential and high stability (>78 h). This work provides new insight into the correlation between the N configuration synergized with a vacancy defect in electrocatalysis.

427 citations


Journal ArticleDOI
TL;DR: In this paper, a structural refinement of room-temperature black-phase CsPbI3 in an orthorhombic polymorph is presented, which is adopted by both powders and thin films of black- phase CsPsPbII3, fabricated either by high- or lowtemperature processes.
Abstract: Room-temperature films of black-phase cesium lead iodide (CsPbI3) are widely thought to be trapped in a cubic perovskite polymorph. Here, we challenge this assumption. We present structural refinement of room-temperature black-phase CsPbI3 in an orthorhombic polymorph. We demonstrate that this polymorph is adopted by both powders and thin films of black-phase CsPbI3, fabricated either by high- or low-temperature processes. We perform electronic band structure calculations for the orthorhombic polymorph and find agreement with experimental data and close similarities with orthorhombic methylammonium lead iodide. We investigate the structural transitions and thermodynamic stability of the various polymorphs of CsPbI3 and show that the orthorhombic polymorph is the most stable among its other perovskite polymorphs, but it remains less stable than the yellow nonperovskite polymorph.

397 citations


Journal ArticleDOI
TL;DR: In this article, the origin of light-induced halide phase segregation, its effects on photovoltaic response, and its effect on tandem solar cells are reviewed, and the effect of the halide migration has been investigated.
Abstract: Hybrid lead halide perovskites such as MAPbI3 (MA = CH3NH3+) and their mixed halide analogues represent an emerging class of materials for solar energy conversion. Intriguing aspects include sizable carrier diffusion lengths, large optical absorption coefficients, and certified power conversion efficiencies that now exceed 22%. Halide-composition-tunable band gaps also make MAPb(I1–xBrx)3 systems ideal candidates for tandem solar cells. Unfortunately, preventing the effective integration of MAPb(I1–xBrx)3 into working devices are intrinsic instabilities due to light-induced halide phase segregation. Namely, under illumination, mixed halide perovskites reversibly segregate into low-band-gap I-rich and high-band-gap Br-rich domains. Under electrical bias, halide migration has also been proposed as the source of undesirable charge injection barriers that degrade photovoltaic performance. In this Perspective, we review the origin of light-induced halide phase segregation, its effects on photovoltaic response,...

386 citations


Journal ArticleDOI
TL;DR: In this paper, a halide perovskite@metal-organic framework (MOF) composite photocatalyst with enhanced CO2 reduction activity was proposed, where a facile in situ synthetic procedure was employed to directly grow a zinc/cobalt-based zeolitic imidazolate framework (ZIF) coating on the surface of quantum dots.
Abstract: The proper energy band structure and excellent visible-light responses enable halide perovskites as potential photocatalysts for CO2 reduction, but the conversion efficiency is still low due to the serious radiative recombination, low CO2 capturing ability, and poor stability. Here we illustrate the design and synthesis of a halide perovskite@metal–organic framework (MOF) composite photocatalyst with enhanced CO2 reduction activity. A facile in situ synthetic procedure is employed to directly grow a zinc/cobalt-based zeolitic imidazolate framework (ZIF) coating on the surface of CsPbBr3 quantum dots. The CsPbBr3@ZIF composite shows largely improved moisture stability, CO2 capturing ability, and charge separation efficiency. Moreover, the catalytic active Co centers in ZIF-67 can further accelerate the charge separation process and activate the adsorbed CO2 molecules, which leads to enhanced catalytic activity for gaseous CO2 reduction. This work would provide new insight for designing excellent perovskite...

Journal ArticleDOI
TL;DR: In this article, an in situ PbBr64-Octahedra passivation strategy was proposed to achieve a 96% absolute QY for the ultrapure (line width = 12 nm) blue emission from CsPbBr3 nanoplatelets (NPLs).
Abstract: Recently, the pursuit of high photoluminescence quantum yields (PLQYs) for blue emission in perovskite nanocrystals (NCs) has attracted increased attention because the QY of blue NCs lags behind those of green and red ones severely, which is fatal for three-primary-color displays. Here, we propose an in situ PbBr64– octahedra passivation strategy to achieve a 96% absolute QY for the ultrapure (line width = 12 nm) blue emission from CsPbBr3 nanoplatelets (NPLs), and both values rank first among perovskite NCs with blue emission. From the aspect of constructing intact PbBr64– octahedra, additional Br– was introduced to drive the ionic equilibrium to form intact Pb–Br octahedra. The reduced Br vacancy and inhibited nonradiative recombination processes are well proved by reduced Urbach energy, increased Pb–Br bonds, and slower transient absorption delay. Blue light-emitting diodes (LEDs) using NPLs were fabricated, and a high external quantum efficiency (EQE) of 0.124% with an emission line width of ∼12 nm wa...


Journal ArticleDOI
TL;DR: In this article, a two-dimensional Ti3C2Tx MXene is employed as a flexible, conductive, and electrochemically active binder for one-step fabrication of MXene-bonded activated carbon as flexible electrode for supercapacitors in an organic electrolyte.
Abstract: We report a strategy to employ two-dimensional Ti3C2Tx MXene as a flexible, conductive, and electrochemically active binder for one-step fabrication of MXene-bonded activated carbon as a flexible electrode for supercapacitors in an organic electrolyte. In this electrode, the activated carbon particles are encapsulated between the MXene layers, eliminating the need for insulative polymer binders. MXene plays a multifunctional role in the electrode, including as a binder, a flexible backbone, a conductive additive, and an additional active material. The synergetic effect of MXene and activated carbon constructs a three-dimensional conductive network and enlarges the distance between the MXene layers, greatly enhancing the electrode capacitance and rate capability. As a result, the flexible MXene-bonded activated carbon electrode exhibits a high capacitance of 126 F g–1 at 0.1 A g–1 and a retention of 57.9% at 100 A g–1 in an organic electrolyte, which is required for developing high-performance, flexible su...

Journal ArticleDOI
TL;DR: In this article, the authors report the electroreduction of CO2 on a supported gold catalyst in an alkaline flow electrolyzer with performance levels close to the economic viability criteria.
Abstract: Cost competitive electroreduction of CO2 to CO requires electrochemical systems that exhibit partial current density (jCO) exceeding 150 mA cm–2 at cell overpotentials (|ηcell|) less than 1 V. However, achieving such benchmarks remains difficult. Here, we report the electroreduction of CO2 on a supported gold catalyst in an alkaline flow electrolyzer with performance levels close to the economic viability criteria. Onset of CO production occurred at cell and cathode overpotentials of just −0.25 and −0.02 V, respectively. High jCO (∼99, 158 mA cm–2) was obtained at low |ηcell| (∼0.70, 0.94 V) and high CO energetic efficiency (∼63.8, 49.4%). The performance was stable for at least 8 h. Additionally, the onset cathode potentials, kinetic isotope effect, and Tafel slopes indicate the low overpotential production of CO in alkaline media to be the result of a pH-independent rate-determining step (i.e., electron transfer) in contrast to a pH-dependent overall process.

Journal ArticleDOI
TL;DR: In this paper, a large-aspect-ratio grain-based thin film with low trap density was developed for high-performance inorganic perovskite CsPbI2Br solar cells.
Abstract: It is imperative to develop a large-aspect-ratio grain-based thin film with low trap density for high-performance inorganic perovskite CsPbI2Br solar cells. Herein, by using Mn2+ ion doping to modulate film growth, we achieved CsPbI2Br grains with aspect ratios as high as 8. It is found that Mn2+ ions insert into the interstices of the CsPbI2Br lattice during the growth process, leading to suppressed nucleation and a decreased growth rate. The combination aids in the achievement of larger CsPbI2Br crystalline grains for increased JSC values as high as 14.37 mA/cm2 and FFs as large as 80.0%. Moreover, excess Mn2+ ions passivate the grain boundary and surface defects, resulting in effectively decreased recombination loss with improved hole extraction efficiency, which enhances the built-in electric field and hence increases VOC to 1.172 V. As a result, the champion device achieves stabilized efficiency as high as 13.47%, improved by 13% compared with only 11.88% for the reference device.


Journal ArticleDOI
TL;DR: In this article, the most common types of plasma reactors with their characteristic features are presented, illustrating why some plasma types exhibit better energy efficiency than others, and highlighting current research in the fields of CO2 conversion (including the combined conversion of CO 2 with CH4, H2O, or H2) as well as N2 fixation (for NH3 or NOx synthesis).
Abstract: Plasma technology is gaining increasing interest for gas conversion applications, such as CO2 conversion into value-added chemicals or renewable fuels, and N2 fixation from the air, to be used for the production of small building blocks for, e.g., mineral fertilizers. Plasma is generated by electric power and can easily be switched on/off, making it, in principle, suitable for using intermittent renewable electricity. In this Perspective article, we explain why plasma might be promising for this application. We briefly present the most common types of plasma reactors with their characteristic features, illustrating why some plasma types exhibit better energy efficiency than others. We also highlight current research in the fields of CO2 conversion (including the combined conversion of CO2 with CH4, H2O, or H2) as well as N2 fixation (for NH3 or NOx synthesis). Finally, we discuss the major limitations and steps to be taken for further improvement.

Journal ArticleDOI
TL;DR: In this paper, a localized high-concentration electrolyte (LHCE) consisting of sodium bis(fluorosulfonyl)imide (NaFSI) and ether solvent was proposed.
Abstract: Sodium (Na) metal is a promising anode for Na-ion batteries. However, the high reactivity of Na metal with electrolytes and the low Na metal cycling efficiency have limited its practical application in rechargeable Na metal batteries. High-concentration electrolytes (HCE, ≥4 M) consisting of sodium bis(fluorosulfonyl)imide (NaFSI) and ether solvent could ensure the stable cycling of Na metal with high Coulombic efficiency but at the cost of high viscosity, poor wettability, and high salt cost. Here, we report that the salt concentration could be significantly reduced (≤1.5 M) by a hydrofluoroether as an “inert” diluent, which maintains the solvation structures of HCE, thereby forming a localized high-concentration electrolyte (LHCE). A LHCE [2.1 M NaFSI/1,2-dimethoxyethane (DME)–bis(2,2,2-trifluoroethyl) ether (BTFE) (solvent molar ratio 1:2)] enables dendrite-free Na deposition with a high Coulombic efficiency of >99%, fast charging (20C), and stable cycling (90.8% retention after 40 000 cycles) of Na∥Na...

Journal ArticleDOI
TL;DR: In this paper, the authors investigate the performance and photostability of metal halide perovskites across a compositional space of formamidinium (FA) and cesium (Cs) at the A-site at various halide compositions.
Abstract: Metal halide perovskites are attractive candidates for the wide band gap absorber in tandem solar cells. While their band gap can be tuned by partial halide substitution, mixed halide perovskites often have lower open-circuit voltage than would be expected and experience photoinduced trap formation caused by halide segregation. We investigate solar cell performance and photostability across a compositional space of formamidinium (FA) and cesium (Cs) at the A-site at various halide compositions and show that using more Cs at the A-site rather than more Br at the X-site to raise band gap is more ideal as it improves both VOC and photostability. We develop band gap maps and design criteria for the selection of perovskite compositions within the CsxFA1–xPb(BryI1–y)3, space. With this, we identify perovskites with tandem-relevant band gaps of 1.68 and 1.75 eV that demonstrate high device efficiencies of 17.4 and 16.3%, respectively, and significantly improved photostability compared to that of the higher Br-co...


Journal ArticleDOI
TL;DR: In this article, a monolithic photocathode device architecture was proposed for unassisted solar water splitting, a pathway to storable renewable energy in the form of chemical bonds, requires optimization of a photoelectrochemical device based on photovoltaic tandem heterojunctions.
Abstract: Efficient unassisted solar water splitting, a pathway to storable renewable energy in the form of chemical bonds, requires optimization of a photoelectrochemical device based on photovoltaic tandem heterojunctions. We report a monolithic photocathode device architecture that exhibits significantly reduced surface reflectivity, minimizing parasitic light absorption and reflection losses. A tailored multifunctional crystalline titania interphase layer acts as a corrosion protection layer, with favorable band alignment between the semiconductor conduction band and the energy level for water reduction, facilitating electron transport at the cathode–electrolyte interface. It also provides a favorable substrate for adhesion of high-activity Rh catalyst nanoparticles. Under simulated AM 1.5G irradiation, solar-to-hydrogen efficiencies of 19.3 and 18.5% are obtained in acidic and neutral electrolytes, respectively. The system reaches a value of 0.85 of the theoretical limit for photoelectrochemical water splittin...

Journal ArticleDOI
TL;DR: In this paper, a promising new family of all-inorganic perovskite (HP) light absorbers based on the nontoxic, earth-abundant, ultrastable Ti(IV) for use in PSCs is reported, which possess a combination of several desirable attributes including suitable bandgaps, excellent optical absorption, benign defect properties, and high stability.
Abstract: The possibility of lead (Pb) contamination and the volatility of the organic cations in the prevailing Pb-based organic-inorganic perovskite (HP) light absorbers are the two key issues of concern in the emerging perovskite solar cells (PSCs). The majority of the Pb-free HP candidates that are being explored for PSCs either suffer from instability issues and have unfavorable defect properties or have unsuitable bandgaps for PSC applications. We report the prediction of a promising new family of all-inorganic HPs based on the nontoxic, earth-abundant, ultrastable Ti(IV) for use in PSCs. We show that the Ti-based HPs possess a combination of several desirable attributes, including suitable bandgaps, excellent optical absorption, benign defect properties, and high stability. In particular, we show experimentally that representative members of the Ti-based HP family, Cs2TiIxBr6–x, have bandgaps that can be tuned between the ideal values of 1.38 and 1.78 eV for single-junction and tandem photovoltaic applicatio...

Journal ArticleDOI
TL;DR: This Perspective discusses the advances in this field of energy research while highlighting the underlying peremptory factors for the rational design of readily tunable COF photoabsorber–cocatalyst systems for optimal photocatalytic performance.
Abstract: Covalent organic frameworks (COFs) are a new class of crystalline organic polymers that have garnered significant recent attention as highly promising H2 evolution photocatalysts. This Perspective discusses the advances in this field of energy research while highlighting the underlying peremptory factors for the rational design of readily tunable COF photoabsorber–cocatalyst systems for optimal photocatalytic performance.

Journal ArticleDOI
TL;DR: Li et al. as mentioned in this paper proposed an ultrasimple and effective strategy to enhance the interfacial connection between garnet SSEs and Li metal just by drawing a graphite-based soft interface with a pencil.
Abstract: Garnet-type solid-state electrolytes (SSEs) are considered to be a good choice for solid-state batteries, yet the interfacial issues with metallic Li limit their applications. Herein, we propose an ultrasimple and effective strategy to enhance the interfacial connection between garnet SSEs and Li metal just by drawing a graphite-based soft interface with a pencil. Both experimental analysis and theoretical calculations confirm that the reaction between the graphite-based interfacial layer and metallic lithium forms a lithiated connection interface with good lithium-ionic and electronic conductivity. Compared to the reported interfacial materials, the graphite provides a soft interface with better ductility and compressibility. With improvement by this soft interface, the impedance of symmetric Li cells significantly decreases and the cell cycle is stable for over 1000 h. Moreover, a solid-state battery with Li-metal anode, ternary NCM523 cathode, and treated-garnet SSEs is fabricated and displays excellen...

Journal ArticleDOI
TL;DR: The most prominent theories are that the X-ides are either completely oxidized, left unoxidized, or transformed into core@shell particles upon testing as mentioned in this paper, but there is a lack of agreement regarding the composition of the true catalyst.
Abstract: Metal chalcogenides, pnictides, and carbides, labeled collectively as metal X-ides, have become an exciting new class of water oxidation electrocatalysts, but there is a lack of agreement regarding the composition of the “true” catalyst. The most prominent theories are that the X-ides are either completely oxidized, left unoxidized, or transformed into core@shell particles upon testing. Here, we examine examples of each conjecture, summarizing the conflicting viewpoints on catalyst identity and offering guidelines for more rigorous identification in the future. Most studies indicate that at least partial oxidation of the catalyst surface is critical to high performance, likely caused by an increased catalyst surface area upon oxidation or improved charge transfer in the X-ide cores. Therefore, more thorough and uniform long-term testing and nanoscale chemical analysis are essential to determine how these factors relate to catalyst performance.

Journal ArticleDOI
TL;DR: In this paper, the benefits of incorporating phenethylammonium cation (PEA+) into (HC(NH2)2PbI3)0.85(CH3NH3PbBr3) 0.15 perovskite for the first time was reported.
Abstract: In this work, we report the benefits of incorporating phenethylammonium cation (PEA+) into (HC(NH2)2PbI3)0.85(CH3NH3PbBr3)0.15 perovskite for the first time. After adding small amounts of PEA cation (<10%), the perovskite film morphology is changed but, most importantly, grain boundaries are passivated. This is supported by Kelvin Probe Force Microscopy (KPFM). The passivation results in the increase in photoluminescence intensity and carrier lifetimes of test structures and open-circuit voltages (VOC) of the devices as long as the addition of PEA+ is ≤4.5%. The presence of higher-band-gap quasi-2D PEA incorporated perovskite is responsible for the grain boundary passivation, and the quasi-2D perovskites are also found to be concentrated near the TiO2 layer, revealed by PL spectroscopy. Results of moisture exposure tests show that PEA+ incorporation is effective in slowing down the degradation of unencapsulated devices compared to the control devices without PEA+. These findings provide insights into the ...

Journal ArticleDOI
TL;DR: It is concluded that Co2P, prepared by thermal phosphidization, dissolves stoichiometrically in acid and degrades to hydroxides under alkaline stability testing.
Abstract: The evaluation of the stability of emerging earth-abundant metal phosphide electrocatalysts by solely electrochemical current–potential sweeps is often not conclusive. In this study, we investigated Co2P to evaluate its stability under both acidic (0.5 M H2SO4) and alkaline (1.0 M KOH) hydrogen evolution (HER) conditions. We found that the electrochemical surface area (ECSA) of Co2P only slightly increased in acidic conditions but almost doubled after electrolysis in alkaline electrolyte. The surface composition of the electrode remained almost unchanged in acid but was significantly altered in alkaline during current–potential sweeps. Analysis of the electrolytes after the stability test shows almost stoichiometric composition of Co and P in acid, but a preferential dissolution of P over Co could be observed in alkaline electrolyte. Applying comprehensive postcatalysis analysis of both the electrode and electrolyte, we conclude that Co2P, prepared by thermal phosphidization, dissolves stoichiometrically ...

Journal ArticleDOI
TL;DR: In this article, the authors present a perspective on the exciting advances of single-atom catalysts for hydrogen evolution reaction (HER) and OER applications, with an emphasis on innovative synthetic strategies and an in-depth understanding of the structure-activity relationship.
Abstract: High-efficiency electrocatalysts with superior activity and stability are crucial to practical applications in water splitting, including the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Downsizing the conventional nanoparticle catalyst to single atoms and constructing single-atom catalysts (SACs) is a rapidly emerging research focus. Because of the involvement of unique single-atom active moieties and the strong metal–support interactions arising from interfacial bonding, SACs as promising alternatives to noble metal-based nanoparticle catalysts exhibit profound power in the HER and OER. Here, we present a perspective on the exciting advances of SACs for HER and OER applications, with an emphasis on innovative synthetic strategies and an in-depth understanding of the structure–activity relationship through a combination of systematic characterization and theoretical studies. Finally, the challenges and some of the critical issues in this field are addressed.

Journal ArticleDOI
TL;DR: In this paper, the role of catalyst composition and process conditions in determining the selective pathways to various products like carbon monoxide, methanol, methane, and dimethyl ether has been overviewed in light of thermodynamic and kinetic considerations.
Abstract: Catalytic conversion of CO2 to chemicals and fuels is a “two birds, one stone” approach toward solving the climate change problem and energy demand–supply deficit in the modern world. Recent advances in mechanistic insights and design of suitable catalysts for direct thermocatalytic hydrogenation of CO2 to C1 products are thoroughly discussed in this Review. The role of catalyst composition and process conditions in determining the selective pathways to various products like carbon monoxide, methanol, methane, and dimethyl ether has been overviewed in light of thermodynamic and kinetic considerations. After extensive elaboration of the main motivation of the reaction pathways, catalytic roles, and reaction thermodynamics, we summarize the most important macroscopic aspects of CO2 hydrogenation technology development, which include reactor innovations, industrial status of the technology, life cycle assessment and technoeconomic analysis. Finally, a critical perspective on the future challenges and opportu...