Showing papers on "Doping published in 2021"
TL;DR: In this paper, a simple boron (B) doping of C3N4/ZnO was proposed to switch from the Z-scheme to type II.
Abstract: Heterojunction photocatalysts are very promising for solar hydrogen production due to their high efficiency in photo-driven charge generation and separation. A C3N4/ZnO heterostructure nanocomposite harvests a wide range of solar light from the UV and visible regions and retains a high redox potential due to its Z-scheme band structure. However, since both C3N4 and ZnO have sufficiently high conduction band energies to drive hydrogen photoreduction, a type II heterojunction is more beneficial for enhancing the hydrogen production efficiency in the current system. In this study, we first demonstrated the charge transfer mechanism switching from the Z-scheme to type II by simple boron (B) doping of C3N4/ZnO. The doping of C3N4 with low-electronegativity boron increases its Fermi level by 0.4 V, making it even higher than that of ZnO. As a result, the Fermi level alignment of B-doped C3N4 with ZnO causes a reversed band bending direction at the C3N4/ZnO junction. The resultant charge transfer switching from the Z-scheme (C3N4/ZnO) to type II (B-doped C3N4/ZnO) was confirmed by UPS and ESR analysis. Type II B-doped C3N4/ZnO shows a stable, drastic increase in the photocatalytic hydrogen evolution rate, approximately 2.9 times higher than that of undoped C3N4/ZnO. The decreased bandgap energy of B-doped C3N4/ZnO also contributes to an additional improvement in efficiency through enhanced light harvesting. Our work presents a simple but effective strategy to design highly capable heterojunction photocatalysts via charge transfer switching with a doping method.
275 citations
TL;DR: In this article, the authors provide a comprehensive review about challenges and solutions to modify Ni-rich layered cathodes specifically for microcrack failure, including surface coating, cation/anion doping, composition tailoring, morphology engineering and electrolytes optimization.
185 citations
TL;DR: In this paper, the authors considered the application of the dopant CeO2 with different concentration on the efficiency of gamma radiation shielding by telluride glasses of type (0.5-x)TeO2-0.25MoO-1.25Bi2O3-xCeO2.
171 citations
TL;DR: In this paper, the authors discuss the underlying fundamentals of semiconductor doping and then investigate different doping strategies in halide perovskites, including intrinsic defect, extrinsic defect and charge transfer doping, from an experimental as well as a theoretical perspective.
Abstract: Electrical doping (that is, intentional engineering of carrier density) underlies most energy-related and optoelectronic semiconductor technologies. However, for the intensely studied halide perovskite family of semiconductors, reliable doping remains challenging, owing to, for example, compensation from and facile migration of intrinsic defects. In this Review, we first discuss the underlying fundamentals of semiconductor doping and then investigate different doping strategies in halide perovskites, including intrinsic defect, extrinsic defect and charge transfer doping, from an experimental as well as a theoretical perspective. We outline the advantages and pitfalls of different characterization techniques to assess doping and examine the impact of doping on optoelectronic properties. Finally, we highlight challenges that need to be overcome to gain control over the electronic properties of this important material class. Halide perovskites exhibit outstanding semiconductor properties and are a key component of a variety of devices, including solar cells and light-emitting diodes. This Review discusses electrical doping strategies for halide perovskites and takes a critical look at the challenges that need to be overcome to control the electronic properties of these semiconducting materials.
132 citations
129 citations
TL;DR: Wang et al. as discussed by the authors proposed a series of oxygen doped K+ implanted carbon nitride (KCN) with narrowed bandgap (2.71−1.62) for the first time.
Abstract: Crystalline carbon nitride (CCN) materials with photoresponse of more than 600 nm are rare. Here, we successfully prepared a series of oxygen doped K+ implanted CCN (KCN) with narrowed bandgap (2.71−1.62 eV) for the first time. Compared with most of the O-doped amorphous CN, the optical absorption can only reach 500 nm, and a few more than 500 nm, our oxygen doping strategy is adopted to activate more n→π* transitions to enhance visible light and even near-infrared light harvesting. This active-optimized O-doped KCN accounts for 45- and 10- times promotion than pristine CN and KCN in H2 generation under λ > 500 nm. Most importantly, its maximum active wavelength is up to 650 nm, which has obvious advantages than most CCN-based photocatalysts in the utilization of solar energy. This excellent solar capture and H2 production is attributed to the activated n→π* electron transition, and high crystallinity and conduction band (CB) position caused by oxygen doping.
111 citations
TL;DR: In this article, a general concept of catalysed n-doping of organic semiconductors using air-stable precursor-type molecular dopants is presented, where the incorporation of a transition metal (for example, Pt, Au, Pd) as vapour-deposited nanoparticles or solution-processable organometallic complexes, as assessed by experimental and theoretical evidence, enables greatly increased η in a much shorter doping time and high electrical conductivities.
Abstract: Chemical doping is a key process for investigating charge transport in organic semiconductors and improving certain (opto)electronic devices1–9. N(electron)-doping is fundamentally more challenging than p(hole)-doping and typically achieves a very low doping efficiency (η) of less than 10%1,10. An efficient molecular n-dopant should simultaneously exhibit a high reducing power and air stability for broad applicability1,5,6,9,11, which is very challenging. Here we show a general concept of catalysed n-doping of organic semiconductors using air-stable precursor-type molecular dopants. Incorporation of a transition metal (for example, Pt, Au, Pd) as vapour-deposited nanoparticles or solution-processable organometallic complexes (for example, Pd2(dba)3) catalyses the reaction, as assessed by experimental and theoretical evidence, enabling greatly increased η in a much shorter doping time and high electrical conductivities (above 100 S cm−1; ref. 12). This methodology has technological implications for realizing improved semiconductor devices and offers a broad exploration space of ternary systems comprising catalysts, molecular dopants and semiconductors, thus opening new opportunities in n-doping research and applications12, 13. Electron doping of organic semiconductors is typically inefficient, but here a precursor molecular dopant is used to deliver higher n-doping efficiency in a much shorter doping time.
101 citations
TL;DR: In this paper, a host-guest organic ultralong room temperature phosphorescence (OURTP) composites with abundant and tunable H-bond network are constructed, which are highly stable in air with ultralough lifetime of 5.08 s at room temperature, and more interestingly, are sensitive to water.
Abstract: Organic ultralong room temperature phosphorescence (OURTP) materials with photophysical properties sensitive to external stimulus are highly attractive for advanced applications. However, most OURTP molecules are in crystal and OURTP materials with good practicability and stimulus-responsive character are hard to be achieved. Here, we report, for the first time, the highly efficient, ultralong-lived and deep-blue OURTP materials by simply doping boron phosphor into cyanuric acid host. Thus constructed host-guest OURTP composites with abundant and tunable H-bond network are highly stable in air with ultralong lifetime of 5.08 s at room temperature, and more interestingly, are sensitive to water, which can strength the H-bond network to significantly enhance OURTP quantum yield from 16.1% to 37.6%. With the extraordinary water-responsive OURTP, anti-counterfeiting paper was facilely prepared for water-jet printing and the jet-printed high-resolution OURTP patterns can be easily erased by solvent fuming for another printing/erasing cycle with high reversibility.
99 citations
TL;DR: In this article, a sulfur(S)-doped Fe1-NC catalyst was obtained as a model, which displays a superior activity for ORR towards the traditional Fe-NC materials.
Abstract: Heteroatom doped atomically dispersed Fe1 -NC catalysts have been found to show excellent activity toward oxygen reduction reaction (ORR). However, the origin of the enhanced activity is still controversial because the structure-function relationship governing the enhancement remains elusive. Herein, sulfur(S)-doped Fe1 -NC catalyst was obtained as a model, which displays a superior activity for ORR towards the traditional Fe-NC materials. 57 Fe Mossbauer spectroscopy and electron paramagnetic resonance spectroscopy revealed that incorporation of S in the second coordination sphere of Fe1 -NC can induce the transition of spin polarization configuration. Operando 57 Fe Mossbauer spectra definitively identified the low spin single-Fe3+ -atom of C-FeN4 -S moiety as the active site for ORR. Moreover, DFT calculations unveiled that lower spin state of the Fe center after the S doping promotes OH* desorption process. This work elucidates the underlying mechanisms towards S doping for enhancing ORR activity, and paves a way to investigate the function of broader heteroatom doped Fe1 -NC catalysts to offer a general guideline for spin-state-determined ORR.
99 citations
97 citations
TL;DR: In this article, the electrical properties of mesoscopic perovskite solar cells were compared with Li-salts with different anions, and the authors found that the anions of the Li-salt dopants affect the electric properties of the electron transfer layers and the solar cell performance.
TL;DR: In this paper, the structural and electronic properties of organic molecule doped MoSi 2N4 monolayers were investigated using first principles calculations to study the effect of molecular doping.
Abstract: MoSi2N4 is a recently developed 2D material that exhibits remarkable thermal, mechanical, electronic, and optical properties. We used first principles calculations to study the structural and electronic properties of organic molecule doped MoSi 2N4 monolayers. Effective p-doping was achieved by molecular doping with tetracyanoquinodimethane and tetracyanoethylene, while n-doping was achieved by molecular doping with tetrathiafulvalene. The doping gap of tetrathiafulvalene-doped MoSi2N4 was successfully modulated by the application of an external electric field, which resulted in effective n-doping. Furthermore, molecular doping injects additional carriers into the host, which is beneficial for enhancing the performance of MoSi2N4 in nanoelectronic devices. Our results demonstrate the importance of molecular doping in tuning the electronic properties of MoSi 2N4 and broadening its applications.
TL;DR: In this paper, the authors reported the construction of atomically dispersed Ni-Ru-P interface sites (ISs) on Ru single-atomic sites doped nickel phosphide nanoparticles (Ru SAs-Ni2P NPs) with high-efficiency HER performances in a wide pH range.
TL;DR: In this article, a series of Sn-doped NiO hollow nanofibers were prepared through a facile electrospinning process followed by heat treatment, and the results indicated that Sn doping could significantly enhance the gas response towards triethylamine at a relative low temperature.
Abstract: High stable triethylamine gas sensors under different relative humidity are highly desirable in order to correctly detect the concentrations of target gas. In this study, a series of Sn-doped NiO hollow nanofibers were prepared through a facile electrospinning process followed by heat treatment. Sn doping could inhibit the crystal growth, and the crystal sizes would decrease with the increase of Sn doping concentration. Gas sensing investigation indicates that Sn doping could significantly enhance the gas response towards triethylamine at a relative low temperature. Especially, the gas sensor exhibits the highest response to triethylamine when the doping content of Sn reaches to 6 at%. The response value is about 16.6–100 ppm triethylamine, and it is ∼9.2 times higher than that of pure NiO nanofibers at the same operating temperature. In addition, the resistances of the gas sensors with different doping contents of Sn would change differently in air or in target gas under variable relative humidity. The resistances in target gas are almost unchanged with the increase of relative humidity with the Sn doping content of 6 at%. It is reasonable to speculate that Sn doping can heavily alter the surface state of NiO nanofibers, which is beneficial for the improvement of the gas response and humidity dependence properties.
TL;DR: In this article, a novel phosphorus-doped Bi2WO6 (PBWO) monolayer with oxygen vacancies was successfully synthesized through a facile one-step hydrothermal treatment using elemental red phosphorus (RP) as P source.
TL;DR: In this article, the role of oxygen doping in photocatalysis was investigated and a simple elemental doping method was proposed to promote charge separation at atomic level and give new insights into highly efficient artificial photosynthesis.
TL;DR: In this paper, a fast and reproducible doping method that involves bubbling a spiro-OMeTAD:LiTFSI solution with CO2 under ultraviolet light is presented.
Abstract: In perovskite solar cells, doped organic semiconductors are often used as charge-extraction interlayers situated between the photoactive layer and the electrodes. The π-conjugated small molecule 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9-spirobifluorene (spiro-OMeTAD) is the most frequently used semiconductor in the hole-conducting layer1-6, and its electrical properties considerably affect the charge collection efficiencies of the solar cell7. To enhance the electrical conductivity of spiro-OMeTAD, lithium bis(trifluoromethane)sulfonimide (LiTFSI) is typically used in a doping process, which is conventionally initiated by exposing spiro-OMeTAD:LiTFSI blend films to air and light for several hours. This process, in which oxygen acts as the p-type dopant8-11, is time-intensive and largely depends on ambient conditions, and thus hinders the commercialization of perovskite solar cells. Here we report a fast and reproducible doping method that involves bubbling a spiro-OMeTAD:LiTFSI solution with CO2 under ultraviolet light. CO2 obtains electrons from photoexcited spiro-OMeTAD, rapidly promoting its p-type doping and resulting in the precipitation of carbonates. The CO2-treated interlayer exhibits approximately 100 times higher conductivity than a pristine film while realizing stable, high-efficiency perovskite solar cells without any post-treatments. We also show that this method can be used to dope π-conjugated polymers.
TL;DR: In this paper, a cation-doping strategy was developed to tailor the electronic structure and catalytic activity of MoSe2 that in situ hybridized with conductive Ti3C2Tx MXene, thus obtaining a Co-MoSe2/MXene bifunctional catalyst as a high-efficient sulfur host.
Abstract: It is a significant challenge to design a dense high-sulfur-loaded cathode and meanwhile to acquire fast sulfur redox kinetics and suppress the heavy shuttling in the lean electrolyte, thus to acquire a high volumetric energy density without sacrificing gravimetric performance for realistic Li-S batteries (LSBs). Herein, we develop a cation-doping strategy to tailor the electronic structure and catalytic activity of MoSe2 that in situ hybridized with conductive Ti3C2Tx MXene, thus obtaining a Co-MoSe2/MXene bifunctional catalyst as a high-efficient sulfur host. Combining a smart design of the dense sulfur structure, the as-fabricated highly dense S/Co-MoSe2/MXene monolith cathode (density: 1.88 g cm-3, conductivity: 230 S m-1) achieves a high reversible specific capacity of 1454 mAh g-1 and an ultrahigh volumetric energy density of 3659 Wh L-1 at a routine electrolyte and a high areal capacity of ∼8.0 mAh cm-2 under an extremely lean electrolyte of 3.5 μL mgs-1 at 0.1 C. Experimental and DFT theoretical results uncover that introducing Co element into the MoSe2 plane can form a shorter Co-Se bond, impel the Mo 3d band to approach the Fermi level, and provide strong interactions between polysulfides and Co-MoSe2, thereby enhancing its intrinsic electronic conductivity and catalytic activity for fast redox kinetics and uniform Li2S nucleation in a dense high-sulfur-loaded cathode. This deep work provides a good strategy for constructing high-volumetric-energy-density, high-areal-capacity LSBs with lean electrolytes.
TL;DR: In this paper, the intrinsic issues in electrochemical HER performance affected by doping heteroatoms (i.e., Sn, Pb, Ti, Nb, V, Li, Cr, Na, Mn, Fe, and Co) are systemically investigated via first-principles calculations and coupled with experimental validation.
Abstract: Investigating the correlations between the changes of electronic structure and catalytic activity is a major requisite for the design and synthesis of the electrocatalysts with promising performance. Herein by using Ni2P as a model electrocatalyst, which is one of the most promising catalysts toward hydrogen evolution reaction (HER), the intrinsic issues in electrochemical HER performance affected by doping heteroatoms (i.e., Sn, Pb, Ti, Nb, V, Li, Cr, Na, Mn, Fe, and Co) are systemically investigated via first-principles calculations and coupled with experimental validation. The results reveal that the increment of Badar charge (ΔQ) and d-band center (ed) on the surface of doped Ni2P catalyst have a significant linear correlation with the hydrogen adsorption energy (ΔGH*). As a result, the ed of Ni atom is found to locate near the optimal region caused by Fe and Co heteroatoms, suggesting that the Fe and Co doped Ni2P should have the best catalytic activity toward HER. Furthermore, the experimental validation process is performed by the synthesis and characterization of the corresponding heteroatom doped Ni2P. The X-ray photoelectron spectroscopy (XPS) reveals that the charge transfer and the shift of ed on the activate site of the doped Ni2P catalyst are consistent with the theoretical analysis. The electrochemical tests demonstrate that Co- and Fe-doped Ni2P catalysts exhibit a Pt-like performance with 31 mV overpotentials at 10 mA cm−2, which is in good agreement with the proposed theory. Our results suggest that the charge redistribution on the surface of the catalysts induced by doping effect is the key to improve their activity, which can be used to guide the design of catalysts in other related catalysis.
TL;DR: In this paper, a novel thiophene group was proposed to extend the optical property of n-π* electronic transitions involving the two lone pairs on sulfur (TLPS) in graphitic carbon nitride (g-C3N4) studies.
TL;DR: In this paper, a P-doped Ni-Mo bimetal aerogel (Ni-Mo-P) was proposed to achieve a current density of 10 mA cm−2.
Abstract: Developing cost-effective bifunctional water splitting electrocatalyst is of significant importance for clean energy applications. Herein, we reported a P-doped Ni-Mo bimetal aerogel (Ni-Mo-P) through facile Ni-Mo aerogel gelation followed by in-situ P doping with NaH2PO4. The optimized Ni-Mo-P catalyst demonstrated impressively low overpotentials of 69 mV and 235 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at a current density of 10 mA cm−2. The excellent HER and OER performance was attributed to the electron redistribution triggered by Mo alloying and P doping as well as the optimal bond strength between H* and the active sites. Density functional theory (DFT) calculations revealed that Ni-Mo-P exhibited a reduced energy barrier and much easier water dissociation originated from the electron redistribution by P doping. Benefiting from these advantages, Ni-Mo-P required a low cell voltage of 1.46 V to achieve an overall water splitting current density of 10 mA cm−2.
TL;DR: New insight is provided into the facile synthesis of visible-light-driven photocatalysts as well as the effect of metal ion doping on the modulation of electronic structures.
TL;DR: In this article, the performance of binary transition metal (Ce & Zn) doped CuO nanocatalyst with liquid ammonia as a pH regulator and precipitating agent was examined using X-ray diffraction, field emission scanning electron microscopy (FESEM), and EDX techniques.
TL;DR: In this paper, the impact of substitutional doping on the electrical and optical properties of van der Waals transition metal dichalcogenides (TMDs) is discussed.
Abstract: Two-dimensional (2D) van der Waals transition metal dichalcogenides (TMDs) are a new class of electronic materials offering tremendous opportunities for advanced technologies and fundamental studies. Similar to conventional semiconductors, substitutional doping is key to tailoring their electronic properties and enabling their device applications. Here, we review recent progress in doping methods and understanding of doping effects in group 6 TMDs (MX2, M = Mo, W; X = S, Se, Te), which are the most widely studied model 2D semiconductor system. Experimental and theoretical studies have shown that a number of different elements can substitute either M or X atoms in these materials and act as n- or p-type dopants. This review will survey the impact of substitutional doping on the electrical and optical properties of these materials, discuss open questions, and provide an outlook for further studies.
TL;DR: In this article, the authors show that low-temperature (2 × 1013 cm-2, sheet resistance as low as ∼7 kΩ/□, and good contact resistance ∼480 Ω·μm in transistors from monolayer MoS2 grown by chemical vapor deposition.
Abstract: Semiconductors require stable doping for applications in transistors, optoelectronics, and thermoelectrics. However, this has been challenging for two-dimensional (2D) materials, where existing approaches are either incompatible with conventional semiconductor processing or introduce time-dependent, hysteretic behavior. Here we show that low-temperature ( 2 × 1013 cm-2, sheet resistance as low as ∼7 kΩ/□, and good contact resistance ∼480 Ω·μm in transistors from monolayer MoS2 grown by chemical vapor deposition. We also reach record current density of nearly 700 μA/μm (>110 MA/cm2) along this three-atom-thick semiconductor while preserving transistor on/off current ratio >106. The maximum current is ultimately limited by self-heating (SH) and could exceed 1 mA/μm with better device heat sinking. With their 0.1 nA/μm off-current, such doped MoS2 devices approach several low-power transistor metrics required by the international technology roadmap.
TL;DR: In this paper, the authors reported a record high ZT of ~0.65 at 623 K in the n-type Ag/In co-doped CoSb3 thin films, fabricated by a facile magnetron sputtering technique.
TL;DR: In this article, a novel life span improving strategy is proposed to modulate the electronic configuration and the layer stacking mode of Mn doped Ni(OH)2 (NiMn-LDH) in situ grown on nickel foam by controlling the Mn doping level.
TL;DR: In this article, the synergistic effect induced by the smaller bandgap, higher charge transfer efficiency, and lower electron-hole recombination rate was used to improve the photocatalytic activity of SnS2 nanoflakes for the treatment of aqueous Cr (VI).
TL;DR: In this article, a metallic and nonmetallic double doping in Co3O4 with nanoneedles structure is reported, which is synthesized through facile oil bath and annealing.
TL;DR: In this paper, the authors proposed a modification strategy for pure TiO in order to eliminate the encountered limitations and thereby enhance the efficiency for further development of photocatalytic applications, which is a process of clean technology where solar energy is converted into useful chemical reactions.
Abstract: Photocatalysis is a process of clean technology where solar energy is converted into useful chemical reactions There are confronted challenges and limitations when claiming the most efficient TiO photocatalytic activity Scientists tend to break through the barriers of TiO photocatalysis by implementing different modification strategies for pure TiO in order to eliminate the encountered limitations and thereby enhance the efficiency for further development of photocatalytic applications Charge carrier recombination is one of the major limitations in the photocatalytic process Doping incorporated with metals and nonmetals owns the capacity to subdue the recombination of photogenerated electrons and holes by ensuring charge carrier separation At the same time, this could enhance the capturing of photoenergy by narrowing the band gap of TiO Dye sensitization is another branch of possible modification of TiO photocatalysis that is implemented in solar electricity generation, photocatalytic water splitting, and pollutant degradation It assists in reduction of transparency in the visible range and obtaining a longer electron lifetime by efficient charge separation Attention is given to the application of TiO photocatalysis based on environmental decontamination, biocidal applications, and energy-based applications Hence, TiO photocatalysis plays a crucial role in reaching higher technological development while maintaining a balance with environmental sustainability