Electrocatalysts For Hydrogen Generation Research Articles

Efficient hierarchical ZIF-based electro/photocatalyst toward hydrogen generation and evolution

In this study, a well-designed hierarchical BiFeO3/ZIF-67 (BFO-ZIF) composite was successfully synthesized to improve the performance of photocatalytic hydrogen generation in comparison to bare BiFeO3 and ZIF-67. Moreover, the behavior of the resultant electrocatalysts was also investigated in the hydrogen evolution reaction (HER). The synthesized electro-photocatalysts were characterized by various physical and photo/electrochemical analyses. The remarkable outcomes of the composite with 50 wt% of ZIF-67 in hydrogen generation correspond to the high specific surface area of the photocatalyst concurrently with the formation of active sites and new charge channels, leading to a modified charge transfer pathway and lower electron-hole recombination. The maximum H2 generation rate over the optimal BFO-ZIF composite (BFO-ZIF(50)) attained 1617 μmol g−1 h−1 during visible light exposure, surpassing the rates observed for pure BFO and ZIF-67. Furthermore, the BFO-ZIF(50) electrocatalyst, with the onset potential of −0.089 V, resulted in an overpotential of −0.19 V at a current density of 10 mA cm−2, while a Tafel slope of 81.6 mV dec−1 in 1.0 M KOH showed the highest activity. The elevated photocatalytic hydrogen generation and improved HER performance of the developed catalysts signify a synergistic effect resulting from the junction and the Z-scheme charge transfer mechanism between the ZIF-67 and BFO nanomaterials. This introduces the BFO-ZIF composite as an efficient photocatalyst and electrocatalyst for hydrogen generation and evolution reaction.

Amorphous Ru Coupled with Defect-Abundant B-Doped FeP4/Fe2P Porous Nanospheres as an Electrocatalyst for Hydrogen Generation with a Wide pH Range

Amorphous Ru Coupled with Defect-Abundant B-Doped FeP₄/Fe₂P Porous Nanospheres as an Electrocatalyst for Hydrogen Generation with a Wide pH Range

Ultrafast Microwave Synthesis of Ru-Doped MoP with Abundant P Vacancies as the Electrocatalyst for Hydrogen Generation in a Wide pH Range.

Molybdenum phosphide (MoP) has received increasing attention for the hydrogen evolution reaction (HER) due to its Pt-like electronic structure and high electrical conductivity. In this work, a flake-like Ru-doped MoP with phosphorus vacancy (Ru-MoP-PV) electrocatalyst is synthesized for the first time by a simple and rapid room-temperature microwave approach within 30 s. The created abundant phosphorus vacancies provide rich active sites and favor rapid electron transfer. The introduced Ru also enhances the catalytic activity of the synthesized electrocatalyst efficiently. Then, the designed Ru-MoP-PV possesses low overpotentials for HER with 79, 100, and 161 mV in 1.0 M KOH, 0.5 M H2SO4, and 1.0 M phosphate-buffered saline to obtain 10 mA cm-2. The Ru-MoP-PV and NiFe-layered double hydroxide are used as the cathode and the anode, respectively, to drive water splitting and just need a low cell voltage of 1.6 V to achieve 10 mA cm-2. This work provides a feasible way for the rapid production of metal phosphides for energy conversion and storage applications.

Direct and in situ growth of 1T′ MoS2 and 1T MoSe2 on electrochemically synthesized MXene as an electrocatalyst for hydrogen generation

Crystal phase modulations in two-dimensional (2D) materials have garnered extensive interest because of their intriguing features and potential applications. Nonetheless, synthesizing some specific phases of metastable transition metal dichalcogenides (TMDs) remains a challenge due to the restricted selectivity under chemical and physical treatments, especially for direct growth of specific phase of TMDs on 2D substrates to form heterostructures. Taking the merits of MXene with tunable atomic vacancies and surface chemistry via surface functionalization, the phase of epitaxially grown TMDs on 2D MXene can be significantly affected. In this work, 1 T′-MoS2 and 1 T-MoSe2 were directly grown on electrochemically synthesized MXene under controlled oxidization conditions and selected MXene substrate. Owing to the synergistic effect of TMDs and MXene, the TMDs/MXene heterostructure catalysts exhibit good electrochemical activity under acidic conditions, with a low overpotential of 167 mV at a current density of 10 mA cm−2. Our work not only demonstrates the distinct chemical characteristic of various MXenes feasible for surface engineering which promotes the direct and in situ growth of phase controlled TMDs on MXene substrates but also displays the high electrochemical activity in TMDs/MXene heterostructure catalysts.

Hydrothermally Derived Hierarchical CuO Nanoflowers as an Efficient Photocatalyst and Electrocatalyst for Hydrogen Evolution

AbstractFabrication of an efficient, economic and earth‐abundant nanocatalyst for H2 production is the centre of attraction in renewable energy technology, but it is still a massive task. In present work, we report a facile modified hydrothermal route to synthesize hierarchical CuO nanoflowers as a noble metal free, proficient photo and electrocatalyst for hydrogen generation. Electrochemical studies were performed over as‐synthesized CuO nanoflowers in both acidic and alkaline medium to record both HER and OER responses. An enhanced HER activity with an overpotential of 1.02 V at −10 mA/cm2 cathodic current density and OER activity with an onset potential at around 1.01 V, respectively, superior to the art of HER and OER bi‐catalyst. Photocatalytic H2 evolution performance exhibits the significant production of 16 mmol/g−1cat in time interval of 8 hours in the presence of Na2S/Na2SO3 sacrificial agent.

(Invited) Commercialization of Catalytic Materials for Chemical and Electrochemical Energy Conversion Technologies

The incredible growth in Electrochemical Energy Conversion Technologies is leading to highly accelerated innovation in the materials at the heart of these technologies. Electrocatalysts for hydrogen generation and conversion, in particular, are experiencing an accelerated adoption cycle when compared to previous deployment, influenced both by volatility and dramatic growth (>60% annually) in precious metal prices. Pajarito Powder has developed and commercialized novel electrocatalysts for fuel cells and electrolyzers. Different applications, the path to commercialization, and both opportunities and challenges to commercialization will be presented, described, and discussed.

1D/2D Cobalt‐Based Nanohybrids as Electrocatalysts for Hydrogen Generation

AbstractThe synergistic effects derived from optimizing the chemical and structural features of electrocatalysts permit them to attain remarkable activity and stability. Herein, 1D/2D cobalt‐based nanohybrid (CoNH) electrodes are developed; the structural design consists of Co3O4 electrospun nanoribbons (NRs) deposited onto a carbon fiber paper substrate where Co3O4 nanosheets are subsequently grown via an electrodeposition step and UV/ozone treatment. The content of noncovalently functionalized carbon nanotubes within the Co3O4 NRs is first tuned to enhance their charge transfer properties and mechanical stability. The electrocatalytic activity of the electrodes is further improved by a phosphorus modification of the 1D NRs, resulting in the formation of NaCoPO4. The optimized 1D/2D CoNH electrode, i.e., ED‐0.09 wt% fCNTs/P‐CoNHs, displays a similar performance to that of platinum in 0.25 m Na2S/0.35 m Na2SO3 (Tafel slope ≈102 mV dec−1 for the former and ≈96 mV dec−1 for the latter) and outstanding stability for up to 48 h. The versatility and high activity of this electrode is also demonstrated according to tests in a conventional water splitting system (cell voltage 1.55V, to produce 10 mA cm−2) and a solar‐driven electrolyzer (1 m KOH).

Synthesis and properties of 1,3-bis[(2-bromo)benzene]triazene and its binuclear silver complex

The reaction of 2-bromoaniline with sodium nitrite affords a triazenido compound, 1,3-bis[(2-bromo)benzene]triazene (HL). Spectroscopic investigations show that HL bears a high selectivity for silver(I) ion in the presence of other metal ions. In the presence of Et3N, the reaction of HL and AgNO3 gives a binuclear triazenido-silver complex, [Ag2(L)2], which has been determined by X-ray diffraction analysis. Electrochemical studies show this silver complex can act as an electrocatalyst for hydrogen generation from neutral water with a turnover frequency (TOF) of 874.14 moles of hydrogen per mole of catalyst per hour (mol H2/mol catalyst/h) at an over potential (OP) of 837.6 mV.

Ruthenium nanoparticles modified oxidized, N-doped carbon substrates: Hydrogen generation electrocatalysts in alkaline and acidic conditions

Various Ru nanoparticles modified porous carbon substrates were prepared as hydrogen evolution electrocatalysts via chemical reduction in this work. Before obtaining the Ru-based catalysts, different carbon substrates, including lignin, straw and shaddock peel, were selected. The carbon substrates were oxidized and nitrogen-doped under ammonia gas to further increase the physicochemical properties. Then, the nitrogen doped lignin, straw and shaddock peel were used as substrates to fabricate various Ru-based composites, which were denoted as Ru@o-NL, Ru@o-NS and Ru@o-NSP. The HER performances of Ru@o-NL, Ru@o-NS and Ru@o-NSP were fully investigated in both acidic and alkaline conditions. Experimental results indicated that all the Ru-based composites could catalyze the hydrogen evolution reaction. Ru@o-NL showed better HER activity than that of the Ru@o-NS and Ru@o-NSP. The dosage of Ru could affect the HER activity. The Ru@o-NL with 8.0 wt% Ru loading has the best HER performance. The overpotentials (@ 10 mA cm−2) of the Ru@o-NL in 0.5 M H2SO4 and 1.0 M KOH were 42 and 14 mV, respectively. The corresponding Tafel slopes were 32 and 59 mV dec−1. It also had large exchange current density and good long term stability.

Effect of metal centers on electrocatalytic hydrogen generation catalyzed by coordinatively saturated metal-1,10-phenanthroline complexes

It is apparent that coordinatively unsaturated transition complexes can catalyze hydrogen production from acid or water via metal-hydride intermediates. To test if coordinatively saturated complexes can also act as electrocatalysts for hydrogen evolution, two electrocatalytic systems based on coordinatively saturated metal-1,10-phenanthroline (phen) complexes, [MII(phen)3](PCPP)2 (PCPP = pentacyanopropenide; M = Fe, 1; Ni, 2), have been designed. The electrochemical investigations show that both 1 and 2 can act as electrocatalysts for hydrogen generation from aqueous buffer with a turnover frequency (TOF) of 630.1 and 673.5 mol of hydrogen per mole of catalyst per hour (mol H2/mol catalyst/h) at an overpotential (OP) of 838 mV. These results also show that the nickel center constitutes the better active catalyst.

Facile synthesis of Ni3S2/rGO nanosheets composite on nickel foam as efficient electrocatalyst for hydrogen evolution reaction in alkaline media

Abstract

Synthesis, characterization and electrocatalytic properties of a tetranuclear triazenido-copper(I) complex

A new molecular catalyst based on a tetra-nuclear copper(I), [CuI4(L)4] 1 is prepared by the reaction of the triazenido ligand, [1,3-bis(2-methoxy)benzene]triazene (HL) with CuCl. X-ray structural studies show that four copper atoms are triazenido-bridged with four independent Cu⋯Cu distances of 2.5881(7)–2.6048(7)Å. Complex 1 can act as an electrocatalyst for hydrogen generation with 170.66mol of hydrogen per mole of catalyst per hour (molh−1) from acetic acid at an overpotential (OP) of 991.6mV and 1034.31molh−1 from a neutral aqueous buffer (pH 7.0) at an OP of 837.6mV, respectively. To test that the triazenido ligand, HL, plays a role in the electrocatalytic system, electrocatalytic activities of HL, CuCl and 1 are each investigated, and a possible catalytic mechanism for hydrogen generation catalyzed by 1 is provided.

A coordinatively saturated nickel complex supported by triazenido ligands: a new electrocatalyst for hydrogen generation via ligand-centered proton-transfer

The reaction of 1,3-bis[2-aminobenzothiazole]triazene (HL) with Ni(CH3CO2)2 affords a nickel complex, [NiII(L)2] 1, an electrocatalyst for hydrogen generation.

Synthesis, characterization and properties of a copper complex with dicyano acetic acid methyl ester ligand derived from tetracyanoethylene

The reaction of CuCl with tetracyanoethylene (TCNE) affords a copper(II) complex, [(DCAE)2Cu(H2O)2] 1 (DCAE: dicyano-acetic acid methyl ester, derived from TCNE). Its structure has been characterized by physics-chemical and spectroscopic methods. Magnetic studies exhibit that no magnetic coupling between two Cu2+ via DCAE− unit in the temperature range 300–9K. Electrochemical studies show that this copper complex can act as an electrocatalyst for hydrogen generation both from acetic acid, with a turnover frequency (TOF) of 74mol of H2 per mole of catalyst per hour an potential (OP) of 941.6 (in CH3CN), and from aqueous buffer (pH 7.0) with a TOF of 285mol of H2 per mole of catalyst per hour at an OP of 787.6mV.

Cobalt and nickel selenide nanowalls anchored on graphene as bifunctional electrocatalysts for overall water splitting

Co and Ni based selenide nanowalls have been prepared on a conductive graphene coated nickel mesh substrate and used as electrocatalysts for hydrogen generation and oxygen evolution. The bifunctional nanowalls manifest a low driven voltage and high structural stability for overall water splitting.

Molybdenum carbide nanocrystal embedded N-doped carbon nanotubes as electrocatalysts for hydrogen generation

Highly conductive N-doped carbon nanotubes embedded with molybdenum carbide nanocrystals with a size less than 3 nm exhibit superior activity for the hydrogen evolution reaction, including small overpotential, large cathodic current density and high exchange current density.

Across the board: Licheng Sun.

In this series of articles the board members of ChemSusChem discuss recent research articles that they consider of exceptional quality and importance for sustainability. In this entry, Prof. Licheng Sun discusses how solar fuel production (such as water splitting) can be made more efficient and economic on an industrial scale. Recommended is the work by Prof. Xuping Sun, who use non-noble metal-phosphorus-based nanostructures as efficient electrocatalysts for hydrogen generation from water.

Photocatalytic generation of hydrogen from water using a cobalt pentapyridine complex in combination with molecular and semiconductor nanowire photosensitizers

Recently, a family of cobalt pentapyridine complexes of the type [(R-PY5Me2)Co(H2O)])(CF3SO3)2, (R = CF3, H, or NMe2; PY5Me2 = 2,6-bis(1,1-di(pyridin-2-yl)ethyl)pyridine) were shown to catalyze the electrochemical generation of hydrogen from neutral aqueous solutions using a mercury electrode. We now report that the CF3 derivative of this series, [(CF3PY5Me2)Co(H2O)](CF3SO3)2 (1), can also operate in neutral water as an electrocatalyst for hydrogen generation under soluble, diffusion-limited conditions on a glassy carbon electrode, as well as a photocatalyst for hydrogen production using either molecular or semiconductor nanowire photosensitizers. Owing to its relatively low overpotential compared to other members of the PY5 family, complex 1 exhibits multiple redox features on glassy carbon, including a one-proton, one-electron coupled oxidative wave. Further, rotating disk electrode voltammetry measurements reveal the efficacy of 1 as a competent hydrogen evolution catalyst under soluble, diffusion-limited conditions. In addition, we establish that 1 can also generate hydrogen from neutral water under photocatalytic conditions with visible light irradiation (λirr ≥ 455 nm), using [Ru(bpy)3]2+ as a molecular inorganic chromophore and ascorbic acid as a sacrificial donor. Dynamic light scattering measurements show no evidence for nanoparticle formation for the duration of the photolytic hydrogen evolution experiments. Finally, we demonstrate that 1 is also able to enhance the hydrogen photolysis yield of GaP nanowires in water, showing that this catalyst is compatible with solid-state photosensitizers. Taken together, these data establish that the well-defined cobalt pentapyridine complex [(CF3PY5Me2)Co(H2O)]2+ is a versatile catalyst for hydrogen production from pure aqueous solutions using either solar or electrical input, providing a starting point for integrating molecular systems into sustainable energy generation devices.