scispace - formally typeset
Search or ask a question

Showing papers on "Nickel published in 2022"


Journal ArticleDOI
TL;DR: In this paper , the integration of Fe dopant and interfacial FeOOH into Ni-MOFs [Fe-doped-(Ni-MOF)/FeOOH] to construct Fe-ONi-O-Fe bonding is demonstrated and elucidate the origin of remarkable electrocatalytic performance.
Abstract: The integration of Fe dopant and interfacial FeOOH into Ni-MOFs [Fe-doped-(Ni-MOFs)/FeOOH] to construct Fe-O-Ni-O-Fe bonding is demonstrated and elucidate the origin of remarkable electrocatalytic performance of Ni-MOFs. X-ray absorption/photoelectron spectroscopy and theoretical calculation results indicate that Fe-O-Ni-O-Fe bonding can facilitate the distorted coordinated structure of Ni site with short nickel-oxygen bond and low coordination number, and can promote the redistribution of Ni/Fe charge density to efficiently regulate the adsorption behavior of key intermediates with near-optimal d-band center. Here the Fe-doped-(Ni-MOFs)/FeOOH with interfacial Fe-O-Ni-O-Fe bonding shows superior catalytic performance for OER with a low overpotential of 210 mV at 15 mA cm-2 and excellent stability with ~3% attenuation after 120 h cycle test. This study will provide a novel strategy to design high-performance Ni/Fe-based electrocatalysts for OER in alkaline media.

110 citations


Journal ArticleDOI
TL;DR: In this article, Fe,Rh-codoped Ni2P nanosheets arrays were in situ anchored on three-dimensional (3D) Ni foam under hydrothermal condition and successive phosphorization.

106 citations


Journal ArticleDOI
TL;DR: In this paper , Fe,Rh-codoped Ni2P nanosheets arrays were in situ anchored on three-dimensional (3D) Ni foam under hydrothermal condition and successive phosphorization.

100 citations


Journal ArticleDOI
TL;DR: In this paper , the as-fabricated Ni cationic vacancies (VNi)−enriched Ni2−xP−VNi electrocatalyst exhibits remarkable 2e ORR performance with H2O2 molar fraction of >95% and Faradaic efficiencies of >90% in all pH conditions under a wide range of applied potentials.
Abstract: Electrocatalytic hydrogen peroxide (H2O2) synthesis via the two‐electron oxygen reduction reaction (2e ORR) pathway is becoming increasingly important due to the green production process. Here, cationic vacancies on nickel phosphide, as a proof‐of‐concept to regulate the catalyst's physicochemical properties, are introduced for efficient H2O2 electrosynthesis. The as‐fabricated Ni cationic vacancies (VNi)‐enriched Ni2−xP‐VNi electrocatalyst exhibits remarkable 2e ORR performance with H2O2 molar fraction of >95% and Faradaic efficiencies of >90% in all pH conditions under a wide range of applied potentials. Impressively, the as‐created VNi possesses superb long‐term durability for over 50 h, suppassing all the recently reported catalysts for H2O2 electrosynthesis. Operando X‐ray absorption near‐edge spectroscopy (XANES) and synchrotron Fourier transform infrared (SR‐FTIR) combining theoretical calculations reveal that the excellent catalytic performance originates from the VNi‐induced geometric and electronic structural optimization, thus promoting oxygen adsorption to the 2e ORR favored “end‐on” configuration. It is believed that the demonstrated cation vacancy engineering is an effective strategy toward creating active heterogeneous catalysts with atomic precision.

96 citations


Journal ArticleDOI
TL;DR: NiCo 2 O 4 NS/PMS system exhibited superior degradation of norfloxacin (NOR) over a wide pH range, and showed higher degradation performance in actual wastewater as discussed by the authors .
Abstract: Developing an ultraefficient heterogeneous catalyst for peroxymonosulfate (PMS) activation at a wide pH range is a challenge. Herein, ultrathin NiCo 2 O 4 nanosheets (NiCo 2 O 4 NS, ~1 nm), with the dominant exposure of (311) facet, was designed for PMS activation. The NiCo 2 O 4 NS/PMS system exhibited superior degradation of norfloxacin (NOR) over a wide pH range. The synergistic effects between Ni and Co were the dominant activation mechanism. Compared with Co 3 O 4 , NiCo 2 O 4 NS adsorb PMS through a unique “bridge” mode, where both Co and adjacent Ni interact with the same O atom in PMS, increasing the number of electron transfer for enhanced breakage of O O bond. NiCo 2 O 4 NS with high cycling stability, could reach 100% degradation of other typical pollutants, and showed higher degradation performance in actual wastewater. This work unveils the intrinsic origin of the superior activity of Co-Ni spinel oxides for PMS activation for the first time, and demonstrates its application potential for organic contaminants degradation. • Ultrathin magnetic NiCo 2 O 4 nanosheet was synthesized by simple annealing hydroxides. • High PMS catalytic activity with 100% pollutant removal could be achieved. • The synergy between Co and Ni on highly active crystal (311) were realized. • Ni increases the Co-O covalency to favor Co-PMS adsorption and charge transfer. • Degradation pathway and intermediates’ ecotoxicity prediction were presented.

95 citations


Journal ArticleDOI
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.

90 citations



Journal ArticleDOI
TL;DR: In this paper , an integrated surface coating/doping strategy is developed to significantly improve the structural stability and electrochemical performance of LiNi0.88Co0.06O2, and the capacity retention of modified material after 200 cycles at 1 C is greatly improved from 59.8% of the pristine material to 87.2%.

81 citations


Journal ArticleDOI
TL;DR: In this paper , a series of bi/multimetallic MOF•74 family materials in situ grown on carbon cloth (CC) by doping Mx+ ions in Ni•MOF−74 is fabricated: NiM−MOF@CC (M = Mn2+, Co2+, Cu2+, Zn2+, Al3+, Fe3+).
Abstract: Limited by single metal active sites and low electrical conductivity, designing nickel‐based metal–organic framework (MOF) materials with high capacity and high energy density remains a challenge. Herein, a series of bi/multimetallic MOF‐74 family materials in situ grown on carbon cloth (CC) by doping Mx+ ions in Ni‐MOF‐74 is fabricated: NiM‐MOF@CC (M = Mn2+, Co2+, Cu2+, Zn2+, Al3+, Fe3+), and NiCoM‐MOF@CC (M = Mn2+, Zn2+, Al3+, Fe3+). The type and ratio of doping metal ions can be adjusted while the original topology is preserved. Different metal ions are confirmed by X‐ray absorption fine structure (XAFS). Furthermore, these Ni‐based MOF electrodes are directly utilized as cathodes for aqueous nickel–zinc batteries (NZBs). Among all the as‐prepared electrodes, NiCo‐MOF@CC‐3 (NCM@CC‐3), with an optimized Co/Ni ratio of 1:1, exhibits the best electrical conductivity, which is according to the density functional theory (DFT) theoretical calculations. The NCM@CC‐3//Zn@CC battery achieves a high specific capacity of 1.77 mAh cm–2, a high areal energy density of 2.97 mWh cm–2, and high cycling stability of 83% capacity retention rate after 6000 cycles. The synthetic strategy based on the coordination effect of metal ions and the concept of binder‐free electrodes provide a new direction for the synthesis of high‐performance materials in the energy‐storage field.

78 citations


Journal ArticleDOI
TL;DR: In this paper , a nanostructured catalyst of nickel phosphides-ruthenium phosphides self-supported on nickel foam (Ni 2 P-Ru 2 P/NF) through an in situ growth-phosphorization process was reported.
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 (Ni 2 P-Ru 2 P/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 Ni 2 P-Ru 2 P/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 Ni 2 P-Ru 2 P/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//RuO 2 /NF (1.64 V) and ranks among the best electrocatalysts previously reported. A high-efficiency bifunctional electrocatalyst for the oxygen evolution reaction and hydrogen evolution reaction was designed by constructing the Ni 2 P-Ru 2 P heterointerfaces on nickel foam. Impressively, the resultant catalyst exhibits outstanding catalytic performance toward overall water splitting. • Self-supported Ni 2 P-Ru 2 P/NF with abundant artificial heterointerfaces is successfully synthesized in situ. • Unique 3D architectures with superhydrophilicity provide large surface area and rich exposed sites. • Ni 2 P-Ru 2 P/NF shows enhanced catalytic performance for OER and HER. • An ultralow cell voltage (1.45 V) and about 100% Faradaic yield toward over water splitting.

74 citations


Journal ArticleDOI
TL;DR: In this paper , the authors reported the synthesis of high efficiency electrocatalysts based on S-doped NiFeP and achieved a current density of 10 mA cm-2 with an overpotential of 201 mV and outperformed most NiFe-based catalysts.
Abstract: Nonprecious transition metal‐organic frameworks (MOFs) are one of the most promising precursors for developing electrocatalysts with high porosity and structural rigidity. This study reports the synthesis of high efficiency electrocatalysts based on S‐doped NiFeP. MOF‐derived S‐doped NiFeP structure is synthesized by a one‐step phosphorization process with using S‐doped MOFs as the precursor, which is more convenient and environment friendly, and also helps retain the samples’ framework. The oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance of the NiFeP catalysts can be improved after partially replacing P by S due to the tunable electronic structure. The optimized CCS‐NiFeP‐10 reaches a current density of 10 mA cm–2 for OER with an overpotential of 201 mV and outperforms most NiFe‐based catalysts. The S doping plays an important role in tuning the ΔG values for intermediates formation in Ni atoms to a suitable value and exhibits a pronouncedly improved the OER performance. CCS‐NiFeP‐20 sample presents excellent HER performance due to the d‐band center downshifting from the Fermi level. When the voltage of the electrolytic cell is 1.50 V, a current density of 10 mA cm–2 can be obtained. This strategy paves the way for designing highly active none‐noble metal catalysts.

Journal ArticleDOI
TL;DR: In this article , a self-sacrificing template strategy was proposed to realize the in situ growth of NiFe-based Prussian blue analogs (NiFe PBA) on Ni3S2 in an interfacial redox reaction.
Abstract: The rational construction of earth‐abundant and advanced electrocatalysts for oxygen evolution reaction (OER) is extremely desired and significant to seawater electrolysis. Herein, by directly etching Ni3S2 nanosheets through potassium ferricyanide, a novel self‐sacrificing template strategy is proposed to realize the in situ growth of NiFe‐based Prussian blue analogs (NiFe PBA) on Ni3S2 in an interfacial redox reaction. The well‐designed Ni3S2@NiFe PBA composite as precursor displays a unique spherical magic cube architecture composed of nanocubes, which even maintains after a phosphating treatment to obtain the derived Ni3S2/Fe‐NiPx on nickel foam. Specifically, in alkaline seawater, the Ni3S2/Fe‐NiPx as OER precatalyst marvelously realizes the ultralow overpotentials of 336 and 351 mV at large current densities of 500 and 1000 mA cm–2, respectively, with remarkable durability for over 225 h, outperforming most reported advanced OER electrocatalysts. Experimentally, a series of characterization results confirm the reconstruction behavior in the Ni3S2/Fe‐NiPx surface, leading to the in situ formation of Ni(OH)2/Ni(Fe)OOH with abundant oxygen vacancies and grain boundaries, which constructs the Ni3S2/Fe‐NiPx reconstruction system responsible for the remarkable OER catalytic activity. Theoretical calculation results further verify the enhanced OER activity for Ni3S2/Fe‐NiPx reconstruction system, and unveil that the Fe‐Ni2P/FeOOH as active origin contributes to the central OER activity.

Journal ArticleDOI
TL;DR: In this paper , a novel p-type nickel-based MOF single crystal (Ni-TBAPy-SC) and its exfoliated two-dimensional (2D) nanobelts showed more efficient charge separation due to its shortened charge transfer distance and remarkably enhanced active surface areas.
Abstract: Development of water-stable metal-organic frameworks (MOFs) for promising visible-light-driven photocatalytic water splitting is highly desirable but still challenging. Here we report a novel p-type nickel-based MOF single crystal (Ni-TBAPy-SC) and its exfoliated nanobelts (Ni-TBAPy-NB) that can bear a wide range of pH environment in aqueous solution. Both experimental and theoretical results indicate a feasible electron transfer from the H4TBAPy ligand (light-harvesting center) to the Ni-O cluster node (catalytic center), on which water splitting to produce hydrogen can be efficiently driven free of cocatalyst. Compared to the single crystal, the exfoliated two-dimensional (2D) nanobelts show more efficient charge separation due to its shortened charge transfer distance and remarkably enhanced active surface areas, resulting in 164 times of promoted water reduction activity. The optimal H2 evolution rate on the nanobelt reaches 98 μmol h-1 (ca. 5 mmol h-1 g-1) showing benchmarked apparent quantum efficiency (AQE) of 8.0% at 420 nm among water-stable MOFs photocatalysts.

Journal ArticleDOI
TL;DR: In this article, self-supported Ni3S2/FeNi2S4 nanosheets (Ni-Fe-S) are synthesized and in-situ Raman measurement is conducted to monitor the phase transformation under realistic conditions.

Journal ArticleDOI
01 May 2022
TL;DR: In this paper , a hybridization of three bimetallic phosphides, nickel-molybdenum (Ni-Mo), cobalt-naphase (CoMo), and cobaltnickel (CoNi), in single ultrathin-3D-nanosheets on nickel foam was carried out to fabricate an active and robust trimetallic metal-phosphide electrocatalyst for overall electrochemical water splitting.
Abstract: Highly efficient electrocatalysts based on non-noble and earth-abundant elements for overall water splitting are of great significance for sustainable energy conversion and storage. Herein, hybridization of three bimetallic phosphides, nickel-molybdenum (Ni–Mo), cobalt-molybdenum (Co–Mo), and cobalt-nickel (Co–Ni), in single ultrathin-3D-nanosheets on nickel foam ([email protected]) was carried out to fabricate an active and robust trimetallic metal-phosphide electrocatalyst for overall electrochemical water splitting. Simple hydrothermal synthesis followed by chemical vapor deposition-based phosphorization was used to fabricate the present catalyst. By using the optimum stoichiometric ratios of metals precursors, [email protected] nanosheets were achieved with the best electrical conductivity and high electrochemically active sites, resulting in high electrocatalytic activities with excellent kinetics for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The [email protected] exhibited a low overpotential of 88 mV at 10 mA cm−2 for HER and a low overpotential of 250 mV at 10 mA cm−2 for OER. The [email protected] (+, -) device required a cell voltage of 1.52 V to reach a current density of 10 mA cm−2 in an alkaline electrolytic solution. The present study demonstrated that [email protected] as the best transition metal phosphide for overall water splitting.

Journal ArticleDOI
TL;DR: In this article , self-supported Ni 3 S 2 /FeNi 2 S 4 nanosheets (Ni-Fe-S) are synthesized and in-situ Raman measurement is conducted to monitor the phase transformation under realistic conditions.

Journal ArticleDOI
TL;DR: In this paper , an improved density functional theory (DFT)-derived d-band theory was provided by considering multi-metals-H bonds cooperative effect as a dependable descriptor of hydrogen adsorption energy and screen out a potential NiCu HER electrocatalyst with a near-optimal Δ G H .
Abstract: Transition-metal alloys are currently drawing increasing attention as promising alkaline hydrogen evolution reaction (HER) electrocatalysts due to their unique advantages. However, traditional density functional theory (DFT)-derived d -band theory fails to describe the hydrogen adsorption energy (Δ G H ) on hollow sites. Herein, by studying the Δ G H for a series of Ni-M (M = Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Mo, W) bimetallic alloys, an improved d -band center is provided by considering multi-metals-H bonds cooperative effect as a dependable descriptor of hydrogen adsorption energy, and screen out a potential NiCu HER electrocatalyst with a near-optimal Δ G H . Moreover, oxygen atoms were introduced into Ni-M (O-NiM) to balance the adsorption/desorption of *OH, the tailored water dissociation electrocatalytic sites can synergistically accelerate the multi-step alkaline HER. Direct experimental evidence is offered that O-NiCu possesses the optimum HER activity with ultralow overpotentials of 23 and 69 mV to obtain current densities of 10 and 100 mA cm -2 , respectively, which is much lower than those of noble metal Pt/C and reported electrocatalysts. The micro-kinetics analysis and DFT calculations further affirm the energetic alkaline HER kinetic process. This work not only broadens the applicability of d -band theory, but provides crucial understanding in designing efficient alkaline HER electrocatalysts.


Journal ArticleDOI
TL;DR: In this article, the effect of concentration variation of reactants (nickel and cobalt ratio) in nickel cobalt phosphate material and their influence on physicochemical properties and electrochemical capacitive performances are investigated.

Journal ArticleDOI
TL;DR: In this article , the authors focus on hydrogen production through reforming processes especially steam and dry reforming and the nickel catalysts' performance for hydrogen production, focusing on effective parameters including mesoporous supports (SBA-15, MCM-41, KIT, and SBA-16).

Journal ArticleDOI
TL;DR: In this article , inorganic nickel oxygenate-derived electrocatalysts can generate linear and branched C3 to C6 hydrocarbons with sustained Faradaic efficiencies of up to 6.5%.
Abstract: The electroreduction of CO2, driven by renewable electricity, can be used to sustainably generate synthetic fuels. So far, only copper-based materials have been used to catalyse the formation of multicarbon products, albeit limited to C2 or C3 molecules. Herein, we disclose that inorganic nickel oxygenate-derived electrocatalysts can generate linear and branched C3 to C6 hydrocarbons with sustained Faradaic efficiencies of up to 6.5%, contrasting with metallic nickel, which is practically inactive. Operando X-ray absorption spectroscopy, electrochemical CO stripping and density functional theory pinpoint the presence of stable, polarized Niδ+ active sites associated with Ni–O bonds, which bind CO moderately. The reduction of selected C1 molecules and density functional theory simulations suggest that the Niδ+ sites promote a mechanism reminiscent of the Fischer–Tropsch synthesis: COOH + CHx coupling followed by successive CHx insertions. Our results disclose atom polarization to be the key that prevents the CO poisoning of nickel and enables CO2 reduction to a wider pool of valuable products. Cu-based catalysts have dominated CO2 electroreduction as a result of their unique ability to produce C2 or C3 products, while Ni has largely been excluded due to poisoning by intermediate CO. Here, inorganic Ni oxygenate-derived electrocatalysts with polarized Ni𝛿+ sites can produce multicarbon products, including C3 to C6 hydrocarbons.

Journal ArticleDOI
TL;DR: In this article , the adsorption behavior of biomaterial activated sawdust-Chitosan nanocomposite beads (SDNCB) powder was investigated along with synthesis and experimental techniques approaches to study the removal efficiency of some heavy metal ions including Ni (II) and Cu(II) ions from aqueous solutions by assessing the surface modified activated carbon by the cost-effective non-conventional method.
Abstract: The adsorption behavior of biomaterial activated Sawdust-Chitosan nanocomposite beads (SDNCB) powder was investigated along with synthesis and experimental techniques approaches to study the removal efficiency of some heavy metal ions including Ni (II) and Cu (II) ions from aqueous solutions by assessing the surface-modified activated carbon by the cost-effective non-conventional method. Structural analysis of the entitled compound was evaluated by the PXRD techniques and its surface morphology was inferred by the following techniques: TEM, EDAX. The behavior of the functional group presents in the compound was discussed using the FTIR technique. Such parameters like dosage, pH, time, temperature, and initial concentration of copper and nickel were associated with this to examine the effect of adsorption of heavy elements that exist in the portable solution. Further, the cellulose and chitosan beads complex material have an appropriate surface area, it demonstrated metal ions removal efficiency was more appreciable due to the action of activated carbon, where this showed fast rate sorption kinetics due to strong involvement of Cu+ & Ni+ towards cellulose and chitosan's functional groups in the bio composite. The isotherm model so-called Langmuir, Freundlich, and Temkin model was utilized to plot the experimental adsorption dataset to infer the maximum adsorption capacity. Based on this model, the adsorption properties of the beads treated compound was determined by plotting the graphs in which sorption intensity (n) which implies expected sorption, and the correlation value are 1.989, 0.998, and 0,981 respectively.

Journal ArticleDOI
TL;DR: In this article, dual-phase electrocatalysts are synthesized by calcining the Ni(OH)2 nanosheets on Ni foam and Se powder under an N2 atmosphere.
Abstract: NiSe2/Ni3Se4 dual-phase electrocatalysts are synthesized by calcining the Ni(OH)2 nanosheets on Ni foam and Se powder under an N2 atmosphere. The Ni’s charge-state, phase compositions, and electrocatalytic performances are dependent on the initial mass ratios of Ni to Se. The experimental results demonstrate that the electrocatalyst with a higher Ni charge-state and more Ni3Se4 phase facilitates oxygen evolution reaction (OER), whereas the one with a lower Ni charge-state and more NiSe2 phase boosts hydrogen evolution reaction (HER). Density functional theory calculations reveal that the interfacial electrons transfer from Ni3Se4 to NiSe2, which improves conductivity and optimizes adsorption/desorption energies. NiSe2/Ni3Se4/NF-4 containing more NiSe2 phase displays the best HER activity while NiSe2/Ni3Se4/NF-1 containing more Ni3Se4 phase shows the best HER activity. The electrolyzer, employing NiSe2/Ni3Se4/NF-4 and NiSe2/Ni3Se4/NF-1 as the cathode and anode, respectively, performs the full potential and demonstrates a low voltage of 1.56 V achieving 10 mA cm-2 with good durability.

Journal ArticleDOI
TL;DR: In this paper, the adsorption behavior of biomaterial activated sawdust-Chitosan nanocomposite beads (SDNCB) powder was investigated along with synthesis and experimental techniques approaches to study the removal efficiency of some heavy metal ions including Ni (II) and Cu(II) ions from aqueous solutions by assessing the surface modified activated carbon by the cost-effective non-conventional method.

Journal ArticleDOI
TL;DR: In this article , a facile one-step molten salt method for the preparation of self-supporting Ni-doped Mo 2 C on carbon fiber paper (Ni-Mo 2 C CB /CFP) for hydrogen evolution reaction (HER) was investigated.
Abstract: Abstract Developing highly efficient and stable non-precious metal catalysts for water splitting is urgently required. In this work, we report a facile one-step molten salt method for the preparation of self-supporting Ni-doped Mo 2 C on carbon fiber paper (Ni-Mo 2 C CB /CFP) for hydrogen evolution reaction (HER). The effects of nickel nitrate concentration on the phase composition, morphology, and electrocatalytic HER performance of Ni-doped Mo 2 C@CFP electrocatalysts was investigated. With the continuous increase of Ni(NO 3 ) 2 concentration, the morphology of Mo 2 C gradually changes from granular to flower-like, providing larger specific surface area and more active sites. Doping nickel (Ni) into the crystal lattice of Mo 2 C largely reduces the impedance of the electrocatalysts and enhances their electrocatalytic activity. The as-developed Mo 2 C-3 M Ni(NO 3 ) 2 /CFP electrocatalyst exhibits high catalytic activity with a small overpotential of 56 mV at a current density of 10 mA·cm −2 . This catalyst has a fast HER kinetics, as demonstrated by a very small Tafel slope of 27.4 mV·dec −1 , and persistent long-term stability. A further higher Ni concentration had an adverse effect on the electrocatalytic performance. Density functional theory (DFT) calculations further verified the experimental results. Ni doping could reduce the binding energy of Mo-H, facilitating the desorption of the adsorbed hydrogen (H ads ) on the surface, thereby improving the intrinsic catalytic activity of Ni-doped Mo 2 C-based catalysts. Nevertheless, excessive Ni doping would inhibit the catalytic activity of the electrocatalysts. This work not only provides a simple strategy for the facile preparation of non-precious metal electrocatalysts with high catalytic activity, but also unveils the influence mechanism of the Ni doping concentration on the HER performance of the electrocatalysts from the theoretical perspective.

Journal ArticleDOI
01 Apr 2022
TL;DR: In this article , dual-phase electrocatalysts are synthesized by calcining the Ni(OH)2 nanosheets on Ni foam and Se powder under an N2 atmosphere.
Abstract: NiSe2/Ni3Se4 dual-phase electrocatalysts are synthesized by calcining the Ni(OH)2 nanosheets on Ni foam and Se powder under an N2 atmosphere. The Ni’s charge-state, phase compositions, and electrocatalytic performances are dependent on the initial mass ratios of Ni to Se. The experimental results demonstrate that the electrocatalyst with a higher Ni charge-state and more Ni3Se4 phase facilitates oxygen evolution reaction (OER), whereas the one with a lower Ni charge-state and more NiSe2 phase boosts hydrogen evolution reaction (HER). Density functional theory calculations reveal that the interfacial electrons transfer from Ni3Se4 to NiSe2, which improves conductivity and optimizes adsorption/desorption energies. NiSe2/Ni3Se4/NF-4 containing more NiSe2 phase displays the best HER activity while NiSe2/Ni3Se4/NF-1 containing more Ni3Se4 phase shows the best HER activity. The electrolyzer, employing NiSe2/Ni3Se4/NF-4 and NiSe2/Ni3Se4/NF-1 as the cathode and anode, respectively, performs the full potential and demonstrates a low voltage of 1.56 V achieving 10 mA cm−2 with good durability.

Journal ArticleDOI
TL;DR: In this paper , the effect of concentration variation of reactants (nickel and cobalt ratio) in nickel cobalt phosphate material and their influence on physicochemical properties and electrochemical capacitive performances are investigated.

Journal ArticleDOI
01 Jan 2022-Polymers
TL;DR: The enhanced electrochemical performances of ASC are congregated by depositing PANI on NF that boosts the electrode's conductivity, which is assured by faster ions diffusion, higher surface area, and ample electroactive sites for better electrolyte interaction.
Abstract: Energy generation can be clean and sustainable if it is dependent on renewable resources and it can be prominently utilized if stored efficiently. Recently, biomass-derived carbon and polymers have been focused on developing less hazardous eco-friendly electrodes for energy storage devices. We have focused on boosting the supercapacitor’s energy storage ability by engineering efficient electrodes in this context. The well-known conductive polymer, polyaniline (PANI), deposited on nickel foam (NF) is used as a positive electrode, while the activated carbon derived from jute sticks (JAC) deposited on NF is used as a negative electrode. The asymmetric supercapacitor (ASC) is fabricated for the electrochemical studies and found that the device has exhibited an energy density of 24 µWh/cm2 at a power density of 3571 µW/cm2. Furthermore, the ASC PANI/NF//KOH//JAC/NF has exhibited good stability with ~86% capacitance retention even after 1000 cycles. Thus, the enhanced electrochemical performances of ASC are congregated by depositing PANI on NF that boosts the electrode’s conductivity. Such deposition patterns are assured by faster ions diffusion, higher surface area, and ample electroactive sites for better electrolyte interaction. Besides advancing technology, such work also encourages sustainability.

Journal ArticleDOI
TL;DR: In this article , the authors presented an interfacial engineering strategy to construct an efficient hydrothermal approach by in situ growing cobalt-doped@MnO2 nanocomposite on highly conductive nickel foam (Ni foam) for supercapacitors.
Abstract: Herein, we present an interfacial engineering strategy to construct an efficient hydrothermal approach by in situ growing cobalt-doped@MnO2 nanocomposite on highly conductive nickel foam (Ni foam) for supercapacitors (SCs). The remarkably high specific surface area of Co dopant provides a larger contacting area for MnO2. In the meantime, the excellent retentions of the hierarchical phase-based pore architecture of the cobalt-doped surface could beneficially condense the electron transportation pathways. In addition, the nickel foam (Ni foam) nanosheets provide charge-transport channels that lead to the outstanding improved electrochemical activities of cobalt-doped@MnO2. The unique cobalt-doped@MnO2 nanocomposite electrode facilitates stable electrochemical architecture, multi-active electrochemical sites, and rapid electro-transports channels; which act as a key factor in enhancing the specific capacitances, stability, and rate capacities. As a result, the cobalt-doped@MnO2 nanocomposite electrode delivered superior electrochemical activities with a specific capacitance of 337.8 F g–1 at 0.5 A g–1; this is greater than pristine MnO2 (277.9 F g–1). The results demonstrate a worthy approach for the designing of high-performance SCs by the grouping of the nanostructured dopant material and metal oxides.

Journal ArticleDOI
TL;DR: In this paper , the effect of escaped inactive ion from pre-catalysts themselves is usually ignored during reconstruction processes, which delivers a promoting effect on OER performance, and an efficient electrocatalyst of Fe incorporated NiMo oxyhydroxide is prepared through an electrochemical strategy for OER.
Abstract: Transition metal-based pre-catalysts undergo drastic reconstruction to form the active catalysts during the alkaline oxygen evolution reaction (OER). However, the effect of escaped inactive ion from pre-catalysts themselves is usually ignored during reconstruction processes. Here, we investigate the effect of inactive MoO 4 2- escaped from a pre-catalyst of Fe incorporated nickel-molybdenum oxyhydroxide (NiMo-Fe) on OER performance. The results of in-situ Raman and X-ray photoelectron spectroscopy reveal that MoO 4 2- can be easily dissolved into KOH electrolyte and re-adsorbed on surface of catalyst during OER processes, which delivers a promoting effect on OER performance. The dissolution of MoO 4 2- is beneficial for increasing the reconstruction degree of NiMo-Fe to form the active phase of NiFeOOH. Theoretical calculations demonstrate that the re-adsorbed MoO 4 2- is favorable for the adsorption of the OOH* intermediate, thus boosts the OER activity. As expected, the NiMo-Fe shows a superior electrocatalytic performance for OER, outperforming the pre-catalyst without Mo species. This finding enriches the knowledge of inactive-ion effect on alkaline OER performance and offers a path for developing efficient electrocatalysts. The promotion effect of the inactive MoO 4 2- on OER performance was discovered and systematic understood. The MoO 4 2- in pre-catalyst is easily dissolved into the KOH electrolyte, which can enhance the reconstruction degree of pre-catalyst to active species. The re-adsorbed MoO 4 2- can improve the OER activity by facilitating adsorption of the OOH* intermediate. • An efficient electrocatalyst of Fe incorporated NiMo oxyhydroxide is prepared through an electrochemical strategy for OER. • The dynamic dissolution and re-adsorption behavior of MoO 4 2- is discovered and contributes to an enhanced OER performance. • The re-adsorbed MoO 4 2- is beneficial for the adsorption of OOH* intermediate, thus promotes OER activity.