Catalysts For Hydrogen Evolution Research Articles

Enhanced photocatalytic hydrogen production from formic acid with reversible electron transfers in PdO/TiO2

A prepared p-type PdO/n-type TiO2 junction was prepared as the catalyst for photocatalytic hydrogen evolution from formic acid (FA). It was found that PdO/TiO2 exhibited 1298-fold higher activity than TiO2 under ultraviolet and visible light irradiation at room temperature. Multiple characterization techniques were utilized to demonstrate that doping PdO into TiO2 can regulate the Fermi level of the sample and the adsorption behavior of FA, resulting in different electron transfer behavior between FA and PdO/TiO2 compared to that between FA and TiO2. Oxygen vacancies acted as electron donors to deliver photogenerated electrons from TiO2 to the adsorbed bidentate FA, which increased the electron density on the O atom of FA and led to the formation of activated monodentate FA. This activated FA was more easily oxidized by the holes in PdO generated by visible light, leading to the production of H2 and CO2. The mode of adsorption associated with the Pd2+ site is the key factor in driving this reaction and leading to the reversible electron transfer phenomenon. This study provides a new promising route for the design of photocatalysts for self-decomposition reactions.

Accelerating Hydrogen Desorption of Nickel Molybdenum Cathode via Copper Modulation for Pure‐Water‐Fed Hydroxide Exchange Membrane Electrolyzer

AbstractThe more sluggish kinetics of hydrogen evolution catalysts in base as compare to that in acid to some degree restricts hydrogen production performance of hydroxide exchange membrane electrolyzers, especially when using earth‐abundant catalysts. Here a ternary nickel–copper–molybdenum hydrogen evolution catalyst is reported that exhibits ≈5 times higher turnover frequency than without copper doping. The X‐ray absorption near‐edge structure and valence band spectrum demonstrate that the light doping of copper into nickel–molybdenum alloy modulates the electronic structure and downshifts the d‐band center, resulting in accelerated hydrogen desorption, as consolidated by H2 temperature programmed desorption and theoretical calculation. An electrolyzer employing this cathode catalyst and a nickel–iron anode, gives a current density of 1.7 A cm−2 at 2.0 V with a pure‐water feed through the anode, which outperforms the 2025 target proposed by the United States Department of Energy, and even is operated continuously for over 1000 h with a decay rate of as low as 0.5 mV h−1. Post‐mortem analysis discloses that hydroxide exchange ionomer migration is one of the key factors affecting long‐term durability. This work demonstrates the feasibility of a low‐cost, water‐fed hydroxide exchange membrane electrolyzer achieving industrial‐level performance and lifetime.

N, P co-doped graphene-supported monometallic nanoparticles for highly efficient hydrogen evolution by acid electrolysis of water

Pt/rGNP exhibits much higher catalytic properties than other transition metal/rGNP catalysts for hydrogen evolution; its overpotential at 100 mA cm−2 in 0.5 M H2SO4 is only 10.6 mV, and its Tafel slope is 14.53 mV dec−1.

Palladium-decorated SiX (X = N, P, As, Sb, Bi) catalysts for hydrogen evolution

Developing single atom catalysts (SAC) is a promising and useful strategy for designing highly efficient and low-cost photo- or electrocatalysts that are active towards hydrogen evolution reaction (HER).

Exploring the degradation mechanism of nickel-copper-molybdenum hydrogen evolution catalysts during intermittent operation.

We investigate the dynamic degradation behaviors of a nickel-copper-molybdenum hydrogen evolution catalyst in a liquid and solid polymer electrolyte to figure out its endurance in a renewable energy-driven electrolyzer. A cathode current protection approach is proposed to achieve a durable electrolyzer during intermittent operation.

Pressed Ni/MFe2O4 (M = Ni, Co) powder compacts for application as bifunctional, high-performance electrodes in electrochemical water splitting

The development of active, stable, earth-abundant, and cheap catalysts is crucial for renewable energy conversion devices. Catalysts for electrochemical water splitting are prepared using cold uniaxial pressing and consist of a superficial ferrite coating on a nickel substrate. The activity and mechanism of the oxygen (OER) and hydrogen (HER) evolution reactions on powder compacts are investigated. It is found that powder compacts are efficient catalysts for oxygen and hydrogen evolution in a 1 M KOH solution. For Ni/NiFe2O4, the current density of 10 mAcm−2 in OER and −10 mAcm−2 in HER shows overpotentials of 272 mV and −43 mV, respectively. In turn, for Ni/CoFe2O4, those overpotentials are 279 mV and −37 mV. Furthermore, using the same material for the anode and cathode in a two-electrode cell configuration, one can achieve a 10 mAcm−2 water splitting current at only 1.55 V for over 48 h without coating degradation. It is stated that the high activity towards OER and HER results from the large electrochemically active surface area and high electrical conductivity of powder compacts. The results also indicate that the most probable rate-determining steps for OER and HER are the formation of the adsorbed oxide atom and H2 molecule, respectively.

Synergistic vacancy defects and bandgap engineering in an Ag/S co-doped Bi2O3-based sulfur oxide catalyst for efficient hydrogen evolution

Herein, an Ag/S co-doped Bi2O3-based sulfur oxide catalyst was prepared via a facile green method.

Modulation and engineering of MOF-derived transition metal selenides/NiFe LDH for application in electrocatalytic hydrogen evolution

The distinctive electronic manipulation and morphology modulation yield an effective bifunctional OER/HER catalyst for electrocatalytic hydrogen evolution.

Porous core–shell structured MoO2–Mo2C@C electrocatalysts for pH-universal hydrogen evolution reaction

We have synthesized an ultra-highly active and stable hydrogen evolution catalyst, MoO2–Mo2C@C, with a porous core–shell structure which can be used under both acidic and alkaline conditions.

Structure transformation induced bi-component Co–Mo/A-Co(OH)2 as highly efficient hydrogen evolution catalyst in alkaline media

Elucidating the inherent origins of the sluggish hydrogen evolution reaction (HER) kinetics in alkaline media and developing high-performance electrocatalysts are fundamental for the advances of conventional alkaline water electrolyzers and emerging anion exchange membrane (AEM) electrolyzers. Here we present a facile electrochemical modification strategy for the synthesis of bi-component Co–Mo(18%)/A-Co(OH)2 catalyst toward efficient HER catalysis in alkaline media. Porous Co–Mo alloys with adjustable Mo/Co atomic ratio are first prepared by H2-assisted cathodic electrodeposition. By virtue of the appropriate electronic structure and hydrogen binding energy, Co–Mo(18%) is the most HER active among the alloys and is further activated by a constant-current electrochemical modification process. Physical characterizations reveal the formation of amorphous Co(OH)2 nanoparticles on the surface. Electrokinetic analysis combined with theoretical calculations reveal that the in-situ formed Co(OH)2 can efficiently promote the water dissociation, resulting in accelerated Volmer-step kinetics. As a result, the Co–Mo(18%)/A-Co(OH)2 simultaneously achieves the optimization of the two factors dominating alkaline HER activity, i.e., water dissociation and hydrogen adsorption/desorption via the bifunctional synergy of the bi-components. The high HER activity (η10 of 47 ​mV at 10 ​mA ​cm−2) of Co–Mo(18%)/A-Co(OH)2 is close to benchmark Pt/C catalyst and comparable or superior to the most active non-noble metal catalysts.

Defective Biphenylene as High-Efficiency Hydrogen Evolution Catalysts.

Electrocatalysts play a pivotal role in advancing the application of water splitting for hydrogen production. This research unveils the potential of defective biphenylenes as high-efficiency catalysts for the hydrogen evolution reaction. Using first-principles simulations, we systematically investigated the structure, stability, and catalytic performance of defective biphenylenes. Our findings unveil that defect engineering significantly enhances the electrocatalytic activity for hydrogen evolution. Specifically, biphenylene with a double-vacancy defect exhibits an outstanding Gibbs free energy of -0.08 eV, surpassing that of Pt, accompanied by a remarkable exchange current density of -3.08 A cm-2, also surpassing that of Pt. Furthermore, we find the preference for the Volmer-Heyrovsky mechanism in the hydrogen evolution reaction, with a low energy barrier of 0.80 eV. This research provides a promising avenue for developing novel metal-free electrocatalysts for water splitting with earth-abundant carbon elements, making a significant step toward sustainable hydrogen production.

Titanium carbide (Ti3C2Tx) decorated molybdenum diselenide (MoSe2) nanoflower composite enhanced photo-electrocatalytic activity in hydrogen evolution

Two-dimensional titanium carbides (Ti3C2Tx) are part of the novel family of transition metal carbides/nitrides known as MXenes, which exhibit a broad range of photo-electrocatalytic applications. In this study, we present a facile hydrothermal synthesis method for Ti3C2Tx decorated on molybdenum diselenide (MoSe2) nanoflower composites, serving as an enhanced catalyst for hydrogen (H2) evolution. Ti3C2Tx, acting as a 2D conductive substrate, facilitates electron transfer, preventing MoSe2 agglomeration, while MoSe2 offers abundant active sites. The characterizations of surface analysis, optical properties, morphological nanostructure, and elemental composition performance of Ti3C2Tx nanosheets, MoSe2 nanoflowers, and Ti3C2Tx/MoSe2 nanoflower composites was conducted using FTIR, XRD, UV–Visible spectroscopy, SEM, EDS Mapping, TEM, and XPS techniques. The catalyst with optimal performance, the Ti3C2Tx/MoSe2 nanoflower composite demonstrates excellent functional properties in the H2 evolution, showing a lower overpotential of 135 mV and smaller Tafel slope of 72 mV/dec at 10 mA/cm2 compared to Ti3C2Tx nanosheets and MoSe2 nanoflowers. The Ti3C2Tx/MoSe2 nanoflower composite forms heterojunctions to inhibit the rapid recombination rate of photo-induced electrons and holes. In comparison to MoSe2 nanoflowers and Ti3C2Tx catalysts (where Tx = F, and O surface terminations), the optimized Ti3C2Tx/MoSe2 nanoflower composite exhibits significantly enhanced photocatalytic activity in H2 production, with a H2 production rate of 2146 μmolg−1h−1 superior than the Ti3C2Tx nanosheets (1367 μmolg−1h−1) and MoSe2 nanoflowers (986 μmolg−1h−1), respectively. Through this design, effective separation of photogenerated charge carriers is achieved, improving the activity of photocatalytic H2 production and demonstrating the promise of the cocatalyst strategy for photocatalysis.

Metal-organic framework derived transition metal sulfides grown on carbon nanofibers as self-supported catalysts for hydrogen evolution reaction

Metal-organic framework (MOF) derived transition metal-based electrocatalysts have received great attention as substitutes for noble metal-based hydrogen evolution catalysts. However, the low conductivity and easy detachments from electrodes of raw MOF have seriously hindered their applications in hydrogen evolution reaction. Herein, we report the facile preparation of Co-NSC@CBC84, a porous carbon-based and self-supported catalyst containing Co9S8 active species, by pyrolysis and sulfidation of in-situ grown ZIF-67 on polydopamine-modified biomass bacterial cellulose (PDA/BC). As a binder-free and self-supported electrocatalyst, Co-NSC@CBC84 exhibits superior electrocatalytic properties to other reported cobalt-based sulfide catalytic materials and has good stability in 0.5 M H2SO4 electrolyte. At the current density of 10 mA cm−2, only an overpotential of 138 mV was required, corresponding to a Tafel slope of 123 mV dec−1, owing to the strong synergy effect between Co-NSC nanoparticles and CBC substrate. This work therefore provides a feasible approach to prepare self-supported transition metal sulfides as HER catalysts, which is helpful for the development of noble metal-free catalysts and biomass carbon materials.

Doping Ni into CoB achieves surface reconstruction to promote efficient electrocatalytic hydrogen evolution reaction

The effective advancement of skilled transition metal electrocatalysts is crucial for promoting the hydrogen evolution reaction (HER) in the process of water splitting. In this context, the integration of nickel (Ni) transition metal atoms into cobalt boride (CoB) is achieved through an electrochemical deposition approach, yielding a remarkably active electrocatalyst termed Ni@CoB for HER. At 10 mA cm−2, the HER overpotential is 63 mV with a Tafel slope of 64.73 mV dec-1. After 50 h of stability testing, there was no significant current decay observed. By employing material characterization techniques and DFT calculations, it has been shown that the incorporation of Ni leads to a surface reconstruction of CoB, thereby decreasing surface aggregation. The catalyst exhibits a uniform spherical porous structure, facilitating enhanced electron transfer. The doped Ni atoms form a bimetallic synergistic effect with Co atoms, not only increasing the stability of interatomic covalent bonds but also enhancing reaction kinetics. This study illuminates the influence of incorporating transition metal atoms into CoB on the activity of HER, presenting a promising strategy for designing high-performance catalysts for alkaline hydrogen evolution.

Supported Manganese Organic Framework as Catalyst for Hydrogen Evolution Reaction

The dependence on fossil fuels has caused significant harmful impact on the environment. The combustion of fossil fuels increases the harmful greenhouse gases including carbon dioxide and methane. The pollution not only worsens the impact of global warming but also affects human health. Many renewable energy sources have been discovered to replace fossil energy, but it is a challenge to find a cheap and effective energy source. Hydrogen arises as a potential candidate due to its high energy density and abundance. However, hydrogen was difficult to store. Hydrogen was often stored in liquid form at high pressure and extremely low temperature conditions. Another method of effectively storing hydrogen is by using hydrogen feedstock materials such as sodium borohydride. Sodium borohydride can be stored at room temperature and has a high gravimetric hydrogen capacity of 10% by weight. However, the process of extracting hydrogen from the materials was slow so it required catalysts. Many precious metal catalysts such as gold and silver catalyst have been applied to improve hydrogen generation reaction, but those metal catalysts were expensive to create. Additionally, those metal catalysts were often agglomerate and impossible to reuse. In this study, we used a non-precious metal complex supported over carbon-based materials to catalyze the hydrogen evolution reaction. We discovered a novel method of synthesizing manganese terephthalate complex at room temperature. The metals complex was coupled with graphene (G) and multiwalled carbon nanotubes (MWCNT) to increase its durability and efficiency. Each material was characterized by Powdered X-ray diffraction (P-XRD), Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). During the reaction with sodium borohydride, we discovered that the manganese terephthalate complex converted to manganese boride and further improved the catalysis process. In the first trial, the reaction catalyzed by Mn complex coupled with MWCNT produced 25ml of hydrogen. At the fifth reuse trials, the amount of generated hydrogen (~44 ml) was nearly doubled. A similar phenomenon was observed in Mn complex coupled with graphene. This study introduces a novel method in synthesizing a stable, cheap and efficient catalyst for hydrogen evolution.

Probing the Effect of Environments on the Stability of Ni2P Nanoparticle Electrocatalysts

Ni2P has been shown to be an effective catalyst for the hydrogen evolution reaction (HER), making it a promising replacement for Pt which is the current state of the art HER catalyst.1,2 H2 is a clean-energy critical fuel and chemical highlighted by the US Department of Energy’s “Hydrogen Shot,” which seeks to reduce “the cost of carbon-neutral hydrogen by 80% to $1 per 1 kg in 1 decade, highlighting the key role of hydrogen in implementing carbon-neutral solutions.”3 Ni2P is also a good or promising catalyst for other reactions, such as alcohol oxidation, hydrodesulfurization,4,5 nitrate reduction, and oxygen evolution reaction.6 However, Ni2P and other TMPs are susceptible to oxidation, which can lead to catalyst degradation and loss in certain conditions.7,8 Stability is an important part of catalysis, especially for achieving the goals of the Hydrogen Shot. Therefore, it is important to understand complex degradation mechanisms in order to better understand structure-activity relationships in these materials. In the present work, in situ Ni K-edge X-ray absorption spectroscopy (XAS) and ex situ P Kα and Kβ X-ray emission spectroscopy (XES) couple together to understand the degradation of Ni2P and show the effects of electrolyte pH, ligands, and air on Ni2P nanoparticles.5 nm Ni2P nanoparticles were synthesized by heating NiCl2 and tris(diethylamino)phosphine in oleylamine. The nanoparticles were drop cast onto carbon fiber paper electrodes and Si wafers or Au-coated wafers for P Kα and Kβ XES. Oleylamine ligands are removed by thermal annealing. Electrochemical experiments were conducted with a three-electrode cell using carbon fiber paper or Au-coated wafers deposited with Ni2P nanoparticles as working electrode, Ag/AgCl calibrated to the H2 redox couple as reference electrode, and graphite rod as counter electrode. P Kα and Kβ XES experiments were conducted inside a N2 glovebox to prevent unintentional air oxidation. Transmission-mode Ni K-edge XAS was conducted on a benchtop spectrometer.Upon exposure to air, as-synthesized Ni2P nanoparticles were studied via P Kα and Kβ XES. Results showed that the phosphide species converted to phosphate with analysis of intermediates well fit by a simple two-phase mixture. Phosphide:phosphate ratios were quantified using linear combination analysis, providing a powerful tool to analyze P speciation on various samples in an inert environment and with minimal loss of material, both advantages of this system over 31P magic angle spinning solid state nuclear magnetic resonance spectroscopy and X-ray photoelectron spectroscopy. Continued work looks at analyzing the effects of the ligand environment on the stability of nanoparticles in electrolytes spanning from acidic to basic pH. We hypothesize that ligands will significantly stabilize the nanoparticles against corrosion and that without ligands Ni2P readily converts to a nickel phosphate species upon exposure to electrolyte.References(1) Popczun, E. J.; McKone, J. R.; Read, C. G.; Biacchi, A. J.; Wiltrout, A. M.; Lewis, N. S.; Schaak, R. E. Nanostructured Nickel Phosphide as an Electrocatalyst for the Hydrogen Evolution Reaction. J. Am. Chem. Soc. 2013, 135 (25), 9267–9270. https://doi.org/10.1021/ja403440e.(2) Liu, P.; Rodriguez, J. A. Catalysts for Hydrogen Evolution from the [NiFe] Hydrogenase to the Ni2P(001) Surface: The Importance of Ensemble Effect. J. Am. Chem. Soc. 2005, 127 (42), 14871–14878. https://doi.org/10.1021/ja0540019.(3) Bullock, M.; More, K. Basic Energy Sciences Roundtable: Foundational Science for Carbon-Neutral Hydrogen Technologies (Report); DOESC Office of Basic Energy Sciences, 2022. https://doi.org/10.2172/1834317.(4) Layan Savithra, G. H.; Muthuswamy, E.; Bowker, R. H.; Carrillo, B. A.; Bussell, M. E.; Brock, S. L. Rational Design of Nickel Phosphide Hydrodesulfurization Catalysts: Controlling Particle Size and Preventing Sintering. Chem. Mater. 2013, 25 (6), 825–833. https://doi.org/10.1021/cm302680j.(5) Rodriguez, J. A.; Kim, J.-Y.; Hanson, J. C.; Sawhill, S. J.; Bussell, M. E. Physical and Chemical Properties of MoP, Ni2P, and MoNiP Hydrodesulfurization Catalysts: Time-Resolved X-Ray Diffraction, Density Functional, and Hydrodesulfurization Activity Studies. J. Phys. Chem. B 2003, 107 (26), 6276–6285. https://doi.org/10.1021/jp022639q.(6) Menezes, P. W.; Indra, A.; Das, C.; Walter, C.; Göbel, C.; Gutkin, V.; Schmeiβer, D.; Driess, M. Uncovering the Nature of Active Species of Nickel Phosphide Catalysts in High-Performance Electrochemical Overall Water Splitting. ACS Catal. 2017, 7 (1), 103–109. https://doi.org/10.1021/acscatal.6b02666.(7) Ha, D.-H.; Han, B.; Risch, M.; Giordano, L.; Yao, K. P. C.; Karayaylali, P.; Shao-Horn, Y. Activity and Stability of Cobalt Phosphides for Hydrogen Evolution upon Water Splitting. Nano Energy 2016, 29, 37–45. https://doi.org/10.1016/j.nanoen.2016.04.034.(8) Parra-Puerto, A.; Ng, K. L.; Fahy, K.; Goode, A. E.; Ryan, M. P.; Kucernak, A. Supported Transition Metal Phosphides: Activity Survey for HER, ORR, OER, and Corrosion Resistance in Acid and Alkaline Electrolytes. ACS Catal. 2019, 11515–11529. https://doi.org/10.1021/acscatal.9b03359.

(Invited) Developing Catalysts and Interfaces for Hydrogen Production By Water Electrolysis and Solar Photoelectrochemistry

Hydrogen is one of the most important molecular commodities in the fuels and chemicals sectors. Developing new pathways to hydrogen production by means of renewable resources could play an important role in meeting global sustainability goals. This paper will focus on the design and development of catalysts and interfaces for hydrogen production. This includes catalysts for hydrogen evolution and oxygen evolution, as well as interfacing those materials within the context of devices for water electrolysis and solar photoelectrochemical (PEC) hydrogen producing systems.

Preparation of Ru/C hydrogen evolution catalyst by mixed salt co-electroreduction of RuCl3*nH2O and CO2

Ruthenium carbon (Ru/C) catalyst is obtained by co-electroreduction of carbonate and ruthenium ions in mixed sodium carbonate, sodium chloride, calcium oxide molten salts (Na2CO3-NaCl-CaO) from carbon dioxide (CO2) and hydrated ruthenium chloride (RuCl3*nH2O). Irregular particles with Ru loaded on carbon, Ru particles coated by carbon and nanocarbon fibers filled with Ru are prepared. Ru/C catalysts with different Ru content of 16.0 wt%, 36.5 wt% and 76.8 wt% are obtained. With the increase of Ru content, the overpotentials (-10 mA cm−2) for HER are respectively 110.8 mV, 198.4 mV, 31.9 mV in strong acid electrolyte (0.5 M H2SO4) and 50.2 mV, 197.9 mV, 16.8 mV in strong alkaline electrolyte (1.0 M KOH). Ru/C prepared at 800 °C, 3.0 V and RuCl3*nH2O content of 1.0 wt% for electrolysis 6 h are of more advantageous for application. The stability of Ru/C catalyst still needs to be improved in 1.0 M KOH. In final, Ru/C electrocatalysts for HER can be successfully prepared by a green route of molten mixed salt from RuCl3*nH2O and CO2.

Frank Partial Dislocations in Coplanar Ir/C Ultrathin Nanosheets Boost Hydrogen Evolution Reaction.

Developing highly active and stable acidic hydrogen evolution catalysts is of great significance and challenge for the long-term operation of commercial proton exchange membrane (PEM) electrolyzers. In this work, coplanar ultrathin nanosheets composed of rich-Frank partial dislocations (FPDs) are first synthesized. Ir nanoparticles and carbon (Dr-Ir/C NSs) use a nonequilibrium high-temperature thermal shock method (>1200 °C) and KBr template-assisted techniques. Dr-Ir/C NSs exhibit excellent hydrogen evolution reaction (HER) performance with a remarkably high mass activity of 6.64 A mg-1 at 50 mV, which is among the best Ir-based catalysts.In addition, Dr-Ir/C NSs are able to operate stably at 1.0 A cm-2 for 200 h as a cathode in a PEM electrolyser, and the original coplanar ultrathin nanosheets structure are maintained after the test, demonstrating excellent stability against stacking and agglomeration. Geometrical phase analysis and theoretical calculations show that the FPDs produce a 4% compressive strain in the Dr-Ir/C NSs, and the compressive strain weaken the adsorption of H* by Ir, thus increasing the intrinsic activity of the catalyst.

Surfacing engineering induced porous CoxPy catalyst for efficient pH universal hydrogen evolution

Designing and synthesizing an effective and robust hydrogen evolution reaction (HER) catalyst is of great significance for hydrogen production from electrochemical water splitting yet remains challenge. Herein, this work reports a porous cobalt phosphide nanoneedles arrays grown a coarsen naked nickel foam (NF/Ni@CoxPy) through a successive electrodeposition–hydrothermal–thermal phosphorization process. Detailed investigation reveals the NF/Ni@CoxPy exhibited a porous structure, leading to the largest double-layer capacitance of 7.6 mF cm–2 and enhanced the hydrophily. In addition, the generation Co-P contains both CoP and Co2P phases, leading to shift of the electronic structure, together to boost the electrocatalytic HER activity. The NF/Ni@CoxPy only needs overpotential of 77, 98, and 71 mV at 10 mA cm–2 in alkaline, buffer solution, and acid solution, respectively. The SCN– probing experiment and in-situ Raman characterization reveal that the Co serves as the active site and the CoxPy reconstructed to Co(OH)2 during HER, which accelerating the fast water dissociation, leading to a lower apparent activation energy of 65.9 kJ mol–1. Hence, this study offers a facial synthesis route to prepare catalyst for HER and provides deep insight into the relationship among coarsen substances, microstructures, and electrocatalytic activity.