Showing papers on "Nickel published in 2021"
TL;DR: In this article, ultrathin rhodium-doped nickel iron layered double hydroxide nanosheets are successfully synthesized, which exhibit outstanding hydrogen evolution reaction (HER) and OER performance, and advanced overall water splitting.
Abstract: Water splitting is a green strategy for hydrogen generation but greatly hindered by the sluggish anodic oxygen evolution reaction (OER). Herein, ultrathin rhodium-doped nickel iron layered double hydroxide nanosheets are successfully synthesized, which exhibit outstanding hydrogen evolution reaction (HER) and OER performance, and advanced overall water splitting. More impressively, the remarkable mass activity of 960 mA mg1 at 1.55 V (1.7 times larger than NiFe-LDH) for urea electro-oxidation reaction (UOR) shows the great potential to surmount the sluggish OER for overall water splitting. A urine-mediated electrolysis cell is subsequently configured, delivering a current density of 10 mA cm-2 with a potential of 1.35 V, which is 105 mV lower than that of urea-free counterpart. The enhanced catalytic activity and cell performance are attributed to the introduction of Rh into NiFe-LDH matrix by changing the electronic structure, allowing optimization of the adsorbed species, as confirmed by experimental measurements and computational analyses.
251 citations
TL;DR: In this article, an unsaturated nickel surface nitride (Ni-SN@C) catalyst that is active and stable for the hydrogen evolution reaction (HER) in alkaline seawater is prepared.
Abstract: Electrocatalytic production of hydrogen from seawater provides a route to low-cost and clean energy conversion. However, the hydrogen evolution reaction (HER) using seawater is greatly hindered by the lack of active and stable catalysts. Herein, an unsaturated nickel surface nitride (Ni-SN@C) catalyst that is active and stable for the HER in alkaline seawater is prepared. It achieves a low overpotential of 23 mV at a current density of 10 mA cm-2 in alkaline seawater electrolyte, which is superior to Pt/C. Compared to conventional transition metal nitrides or metal/metal nitride heterostructures, the Ni-SN@C has no detectable bulk nickel nitride phase. Instead, unsaturated NiN bonding on the surface is present. In situ Raman measurements show that the Ni-SN@C performs like Pt with the ability to generate hydronium ions in a high-pH electrolyte. The catalyst operation is then demonstrated in a two-electrode electrolyzer system, coupling with hydrazine oxidation at the anode. Using this system, a cell voltage of only 0.7 V is required to achieve a current density of 1 A cm-2 .
187 citations
TL;DR: The interaction between CR molecules and nickel-based adsorbents is systematically presented, the possible adsorption mechanisms are summarized, and the challenges and future development directions of the practical application of nickel- based adsorbent materials are proposed.
134 citations
TL;DR: In this article, a Ni/CeO2 catalyst was prepared via decomposition of nickel precursor by gas discharge plasma, followed by hydrogen reduction thermally, and the activity of the obtained catalyst reached the highest level towards CO2 methanation with methane selectivity above 99 % at reaction temperatures lower than 300 °C.
Abstract: A Ni/CeO2 catalyst was prepared via decomposition of nickel precursor by gas discharge plasma, followed by hydrogen reduction thermally. The activity of the obtained catalyst reaches the highest level towards CO2 methanation with methane selectivity above 99 % at reaction temperatures lower than 300 °C. For example, the CH4 formation rate at 275 °C is 100.3 μmol gcat−1 s−1, higher than the reported catalysts at the same reaction temperature. Characterization results indicate that the plasma decomposition leads to an interfacial structure where Ni atoms bind with O atoms from ceria. A strong metal-support interaction is caused. Rich interfacial Ni-CeO2 sites are thus formed with excellent redox property. The unique interfacial structure confines small nickel particles on the ceria surface, exposing more metallic Ni as active sites for splitting H2. Therefore, the plasma prepared Ni/CeO2 catalyst shows balanced active sites for H2 splitting and CO2 activation, improving low temperature catalytic activity significantly.
127 citations
127 citations
TL;DR: In this paper, a graphitic carbon nitride support was used for the semi-hydrogenation of acetylene in excess ethylene, where the active nickel site confined in two stable hydroxylated copper grippers dynamically changes by breaking the interfacial nickel-support bonds on reactant adsorption.
Abstract: Atomically dispersed metal catalysts maximize atom efficiency and display unique catalytic properties compared with regular metal nanoparticles. However, achieving high reactivity while preserving high stability at appreciable loadings remains challenging. Here we solve the challenge by synergizing metal–support interactions and spatial confinement, which enables the fabrication of highly loaded atomic nickel (3.1 wt%) along with dense atomic copper grippers (8.1 wt%) on a graphitic carbon nitride support. For the semi-hydrogenation of acetylene in excess ethylene, the fabricated catalyst shows extraordinary catalytic performance in terms of activity, selectivity and stability—far superior to supported atomic nickel alone in the absence of a synergizing effect. Comprehensive characterization and theoretical calculations reveal that the active nickel site confined in two stable hydroxylated copper grippers dynamically changes by breaking the interfacial nickel–support bonds on reactant adsorption and making these bonds on product desorption. Such a dynamic effect confers high catalytic performance, providing an avenue to rationally design efficient, stable and highly loaded, yet atomically dispersed, catalysts. Synergizing metal–support interactions and spatial confinement through atomic copper grippers boost the dynamics of highly loaded atomic nickel for high activity, high thermal/chemical stability and unprecedented coke inhibition in hydrogenation reactions.
109 citations
TL;DR: This minireview provides an overview of the state-of-the-art approaches for mild C-heteroatom bond formations and highlights the developments in photoredox and nickel dual catalysis involving SET and energy transfer processes; photoexcited nickel cataylsis; electro and nickelDual catalysis; heterogeneous photored Oxidation; and more conventional zinc and Nickel dual catalyzed reactions.
Abstract: The formation of C-heteroatom bonds represents an important type of bond-forming reaction in organic synthesis and often provides a fast and efficient access to privileged structures found in pharmaceuticals, agrochemical and materials. In contrast to conventional Pd- or Cu-catalyzed C-heteroatom cross-couplings under high-temperature conditions, recent advances in homo- and heterogeneous Ni-catalyzed C-heteroatom formations under mild conditions are particularly attractive from the standpoint of sustainability and practicability. The generation of NiIII and excited NiII intermediates facilitate the reductive elimination step to achieve mild cross-couplings. This review provides an overview of the state-of-the-art approaches for mild C-heteroatom bond formations and highlights the developments in photoredox and nickel dual catalysis involving SET and energy transfer processes; photoexcited nickel catalysis; electro and nickel dual catalysis; heterogeneous photoredox and nickel dual catalysis involving graphitic carbon nitride (mpg-CN), metal organic frameworks (MOFs) or semiconductor quantum dots (QDs); as well as more conventional zinc and nickel dual catalyzed reactions.
108 citations
TL;DR: In this article, bimetallic nickel cobalt phosphide and N, P-doped carbon composite (NiCoP/NPC) with folded and hollow spherical structures were first synthesized using a facile ionic liquid-assisted approach.
Abstract: Herein, bimetallic nickel cobalt phosphide and N, P-doped carbon composite (NiCoP/NPC) with folded and hollow spherical structures were first synthesized using a facile ionic liquid-assisted approach. The abundant folds increased the specific surface area by five times compared to the sample without adding ionic liquid. The carbon composites doped with N and P atoms lead to faster electron transfer and more active sites, as verified by density functional theory (DFT). When used as a catalyst, the overpotentials for HER at a current density of 10 mA cm−2 were 108, 128 and 106 mV in acidic, alkaline and neutral media, respectively. Moreover, the optimally structured also showed superior electrochemical performance in an asymmetric supercapacitor with an energy density as high as 26.8 Wh kg−1 at the power density of 7973.0 W kg−1. This study offers a valuable reference for the rational design and synthesis to improved composite surface area and element-doping.
107 citations
TL;DR: In contrast to other Ni‐based intermetallic precatalysts under alkaline OER conditions, an unexpected electroconversion of NiGe into γ‐NiIIIOOH with intercalated OH−/CO3 2− transpired that served as a highly active structure as shown by various ex‐situ methods and quasi in-situ Raman spectroscopy.
Abstract: Identifying novel classes of precatalysts for the oxygen evolution reaction (OER by water oxidation) with enhanced catalytic activity and stability is a key strategy to enable chemical energy conversion. The vast chemical space of intermetallic phases offers plenty of opportunities to discover OER electrocatalysts with improved performance. Herein we report intermetallic nickel germanide (NiGe) acting as a superior activity and durable Ni-based electro(pre)catalyst for OER. It is produced from a molecular bis(germylene)-Ni precursor. The ultra-small NiGe nanocrystals deposited on both nickel foam and fluorinated tin oxide (FTO) electrodes showed lower overpotentials and a durability of over three weeks (505 h) in comparison to the state-of-the-art Ni-, Co-, Fe-, and benchmark NiFe-based electrocatalysts under identical alkaline OER conditions. In contrast to other Ni-based intermetallic precatalysts under alkaline OER conditions, an unexpected electroconversion of NiGe into γ-NiIII OOH with intercalated OH- /CO3 2- transpired that served as a highly active structure as shown by various ex situ methods and quasi in situ Raman spectroscopy.
106 citations
TL;DR: In this paper, the photocatalytic activity for degradation of methylene blue dye was investigated under UV light irradiation and compared with hydrogen peroxide-assisted and catalytic HPC degradation, catalytic HPO oxidation, and adsorption processes for dye removal from aqueous solution.
100 citations
TL;DR: In this paper, a porous and self-supported FeNi-alloy fiber paper is successfully fabricated to achieve excellent OER performance with an ultralow overpotential, as well as remarkable stability.
Abstract: High-performance and low-cost electrocatalysts for oxygen evolution reaction (OER) are urgently desired to improve the overall efficiency of electrochemical water splitting. Here, a porous and self-supported FeNi-alloy fiber paper is successfully fabricated to achieve excellent OER performance with an ultralow overpotential, as well as remarkable stability. It is demonstrated that Fe substitution into metallic nickel can enable the inactive metallic nickel to endow highly electrocatalytic activity. Therefore, Fe substitution plays a key role for the outstanding performance. Specifically, the leaching of partial Fe atoms on surface of alloy facilitates surface reconstruction to generate active FeNi-oxyhydroxides under OER conditions. Meanwhile, Fe atoms can induce the lengthening of Ni-O bonds within oxyhydroxides for promoting the decomposition of *OOH intermediate species into O2. This work provides new insights into the underlying mechanisms of Fe substitution into metal nickel for improving OER activity, which can accelerate the exploitation of low-cost, efficient and durable electrocatalysts.
TL;DR: In this paper, Ni(OH)2 is modified by platinum to adjust the electronic structure and the current density of HMFOR improves 8.2 times at the Pt/Ni(OH)-2 electrode compared with that on Ni(O)2 electrode.
Abstract: Nickel hydroxide (Ni(OH)2 ) is a promising electrocatalyst for the 5-hydroxymethylfurfural oxidation reaction (HMFOR) and the dehydronated intermediates Ni(OH)O species are proved to be active sites for HMFOR. In this study, Ni(OH)2 is modified by platinum to adjust the electronic structure and the current density of HMFOR improves 8.2 times at the Pt/Ni(OH)2 electrode compared with that on Ni(OH)2 electrode. Operando methods reveal that the introduction of Pt optimized the redox property of Ni(OH)2 and accelerate the formation of Ni(OH)O during the catalytic process. Theoretical studies demonstrate that the enhanced Ni(OH)O formation kinetics originates from the reduced dehydrogenation energy of Ni(OH)2 . The product analysis and transition state simulation prove that the Pt also reduces adsorption energy of HMF with optimized adsorption behavior as Pt can act as the adsorption site of HMF. Overall, this work here provides a strategy to design an efficient and universal nickel-based catalyst for HMF electro-oxidation, which can also be extended to other Ni-based catalysts such as Ni(HCO3 )2 and NiO.
TL;DR: In this paper, an as-synthesized P-doped NiMoO4/MoO2 heterostructure nanorods exhibit an extraordinary low overpotential of −23 mV at a current density of 10 mA cm−2, which is highly comparable to the performance of the state-of-theart Pt/C coated on nickel foam (NF) catalyst.
TL;DR: In this article, the combination of anodic preparation of the alkoxy triphenylphosphonium ion and nickel-catalyzed cathodic reductive cross-coupling provides an efficient method to construct C(sp2)-C(sp3) bonds, in which free alcohols and bromides can be directly used as coupling partners.
Abstract: As alcohols are ubiquitous throughout chemical science, this functional group represents a highly attractive starting material for forging new C-C bonds. Here, we demonstrate that the combination of anodic preparation of the alkoxy triphenylphosphonium ion and nickel-catalyzed cathodic reductive cross-coupling provides an efficient method to construct C(sp2)-C(sp3) bonds, in which free alcohols and aryl bromides-both readily available chemicals-can be directly used as coupling partners. This nickel-catalyzed paired electrolysis reaction features a broad substrate scope bearing a wide gamut of functionalities, which was illustrated by the late-stage arylation of several structurally complex natural products and pharmaceuticals.
TL;DR: In this article, a Y2O3-promoted NiO-CeO2 catalyst was proposed and found to exhibit an outstanding methanation activity that is up to three folds higher than NiOCe O2 and six fold higher than NO-Y 2 O3 at mild reaction temperatures.
Abstract: It is challenging to elucidate the mechanism of CO2 methanation reaction over nickel-based catalysts and precisely tune the kinetics of rate-determining-step. In this work, we propose a strategy to engineer the oxygen vacancies of nickel-based catalysts for enhanced CO2 methanation. A Y2O3-promoted NiO-CeO2 catalyst is prepared and found to exhibit an outstanding methanation activity that is up to three folds higher than NiO-CeO2 and six folds higher than NiO-Y2O3 at mild reaction temperatures (
TL;DR: In this article, the authors proposed earth-abundant non-noble metals based catalysts for alkaline water electrolysis in sustainable hydrogen economies, however, such catalysts often suffer from high overp...
Abstract: Catalysts based on earth-abundant non-noble metals are interesting candidates for alkaline water electrolysis in sustainable hydrogen economies. However, such catalysts often suffer from high overp ...
TL;DR: Amorphous Ni sulfoselenide on the surface of Ni(OH)2 nanoplate that is supported by nickel foam is synthesized, which demonstrates high activity and durability for hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) in alkaline media.
TL;DR: In this article, a self-supported nanoflower-like electrocatalyst composed of ultrathin nanosheets on carbon fiber paper (CFP) was synthesized via a molten salt method.
Abstract: Developing an efficient, stable and low-cost noble-metal-free electrocatalyst for the hydrogen evolution reaction (HER) is an effective way to alleviate the energy crisis. Herein, we report a simple and facile approach to synthesize self-supported Ni-doped Mo2C via a molten salt method. By optimizing the content of Ni, the concentration of Ni(NO3)2, and the annealing time, self-supported nanoflower-like electrocatalysts composed of ultrathin nanosheets on carbon fiber paper (CFP) can be achieved. Such a fluffy and porous nanoflower-like structure has a large specific surface area, which can expose many active sites, and promote charge transfer; moreover, all of the above is beneficial for improving the HER performance. Density functional theory (DFT) calculations reveal that the doping of Ni leads to a down shift of the value of the d band center (ed), so that the adsorbed hydrogen (Hads) is easier to desorb from the catalyst surface, thus leading to an enhanced intrinsic catalytic activity of Ni doped Mo2C based catalysts. As a result, Mo2C-3 M Ni(NO3)2/CFP with a nanoflower-like structure prepared at 1000 °C for 6 h exhibits the best electrocatalytic performance for the HER in 0.5 M H2SO4, with a low overpotential of 56 mV (at j = 10 mA cm-2) and a Tafel slope (27.4 mV dec-1) comparable to that of commercial Pt/C (25.8 mV dec-1). The excellent performance surpasses most of the noble-metal-free electrocatalysts. In addition, the outstanding long-term durability of Mo2C-3 M Ni(NO3)2/CFP is demonstrated by showing no obvious fluctuations during 35 h of the HER testing. This work provides a simple and facile strategy for the preparation of nanoelectrocatalysts with high specific surface areas and high catalytic activities, both of which promote an efficient HER.
TL;DR: In this article, a hydroxide-mediated nickel-based electrocatalyst for high-current-density hydrogen evolution was reported, which delivered a current density of 1000 mA cm−2 at an ultralow overpotential of 97 mV.
Abstract: Large-scale production of green hydrogen by electrochemical water splitting is considered as a promising technology to address critical energy challenges caused by the extensive use of fossil fuels. Although nonprecious nickel-based catalysts work well at low current densities, they need large overpotentials at high current densities, which hinders their wide applications in practical industry. Here we report a hydroxide-mediated nickel-based electrocatalyst for high-current-density hydrogen evolution, which delivers a current density of 1000 mA cm−2 at an ultralow overpotential of 97 mV. Combined X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) results show charge redistribution of Ni sites caused by Mo and surface Fe, which can stabilize the surface nickel hydroxide at high current densities for promoting the water dissociation step. Combined in situ XAS, quasi in situ XPS, and density functional theory calculations indicate that Fe plays an important role in the improved catalytic activity. Such a catalyst is synthesized at the metre-size scale and delivers a current density of 500 mA cm−2 at 1.56 V in overall water splitting, demonstrating its potential for practical use. This work highlights a charge engineering strategy to design efficient catalysts for high current density electrochemical applications.
TL;DR: In this paper, the most promising cathodes for next-generation lithium-ion batteries in electric vehicles are the NiNi1−y−zMnyCozO2 (1 − y − z ≥ 0.8) materials.
Abstract: Nickel-rich layered metal oxide LiNi1–y–zMnyCozO2 (1 – y – z ≥ 0.8) materials are the most promising cathodes for next-generation lithium-ion batteries in electric vehicles. However, they lose more...
TL;DR: In this paper, a new microporous organic-inorganic hybrid nickel phosphonate (NiPPA) material was synthesized under hydrothermal reaction condition without the use of structure directing agent.
TL;DR: In this article, a simple and robust electrodeposition technique to prepare NiFe-LDH/Ni(OH)2 composite for hydrogen evolution reaction (HER) and overall water splitting was proposed.
TL;DR: Ni2P-Ru2P/NF as discussed by the authors is a nanostructured catalyst of nickel phosphides-ruthenium phosphides self-supported on nickel foam, which exhibits enhanced electrocatalytic behavior for the oxygen evolution reaction and hydrogen evolution reaction.
Abstract: Rational design and exploitation of efficient and inexpensive catalysts for water electrolysis are highly desired, yet very challenging. Herein, for the first time, we report a nanostructured catalyst of nickel phosphides-ruthenium phosphides self-supported on nickel foam (Ni2P-Ru2P/NF) through an in situ growth-phosphorization process. As expected, by virtue of prominent intrinsic activity, rich electrochemically active sites, and high electronic conductivity, the resultant Ni2P-Ru2P/NF exhibits enhanced electrocatalytic behavior for the oxygen evolution reaction and hydrogen evolution reaction, which delivers low overpotentials of 160 and 101 mV at 10 mA cm 2 in alkaline media, respectively. Remarkably, the Ni2P-Ru2P/NF can dramatically accelerate full water splitting with an ultralow cell voltage of 1.45 V at 10 mA cm-2, which far exceeds the benchmark Pt-C/NF//RuO2/NF (1.64 V) and ranks among the best electrocatalysts previously reported.
TL;DR: In this paper, a quasi-solid-state template strategy was proposed to synthesize highly dispersed supported metal catalysts on nitrogen-doped carbon (M-N-C) with a large fraction of single atom Ni species, in which dispersion of metal precursor, evaporation of solvent and downsizing of templates can be simultaneously achieved during the one-step ballmilling process.
TL;DR: In this paper, an ultrathin nickel-incorporated cobalt phosphide porous nanosheets (Ni-CoP) featuring an atomic heterometallic site (NiCo16-xP6) via a boron-assisted method was fabricated.
Abstract: Identification of active sites for highly efficient catalysts at the atomic scale for water splitting is still a great challenge. Herein, we fabricate ultrathin nickel-incorporated cobalt phosphide porous nanosheets (Ni-CoP) featuring an atomic heterometallic site (NiCo16-xP6) via a boron-assisted method. The presence of boron induces a release-and-oxidation mechanism, resulting in the gradual exfoliation of hydroxide nanosheets. After a subsequent phosphorization process, the resultant Ni-CoP nanosheets are implanted with unsaturated atomic heterometallic NiCo16-xP6 sites (with Co vacancies) for alkaline hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The optimized Ni-CoP exhibits a low overpotential of 88 and 290 mV at 10 mA cm-2 for alkaline HER and OER, respectively. This can be attributed to reduced free energy barriers, owing to the direct influence of center Ni atoms to the adjacent Co/P atoms in NiCo16-xP6 sites. These provide fundamental insights on the correlation between atomic structures and catalytic activity.
TL;DR: In this article, the authors reported the synthesis of two-dimensional metal-organic frameworks (MOFs) on nickel foam (NF) by assembling nickel chloride hexahydrate and 1,1'-ferrocenedicarboxylic acid (NiFc-MOF/NF).
Abstract: We report the synthesis of two-dimensional metal-organic frameworks (MOFs) on nickel foam (NF) by assembling nickel chloride hexahydrate and 1,1'-ferrocenedicarboxylic acid (NiFc-MOF/NF). The NiFc-MOF/NF exhibits superior oxygen evolution reaction (OER) performance with an overpotential of 195 mV and 241 mV at 10 and 100 mA cm-2 , respectively under alkaline conditions. Electrochemical results demonstrate that the superb OER performance originates from the ferrocene units that serve as efficient electron transfer intermediates. Density functional theory calculations reveal that the ferrocene units within the MOF crystalline structure enhance the overall electron transfer capacity, thereby leading to a theoretical overpotential of 0.52 eV, which is lower than that (0.81 eV) of the state-of-the-art NiFe double hydroxides.