Earth‐Abundant Metal‐Based Electrocatalysts Promoted Anodic Reaction in Hybrid Water Electrolysis for Efficient Hydrogen Production: Recent Progress and Perspectives

Abstract

Figure 14. a) Schematic diagram of the ammonia-assisted HWE electrolyzer. b) LSVs curves of LNCO55-Ar and Pt/C. c) Electrolysis current density at 1.23 V, and d) the concentration profile of ammonia and removal efficiency of LNCO55-Ar. Reproduced with permission. [219] Copyright 2021, Wiley-VCH. e) Schematic illustration of the AmOR over ternary NiCuFe oxyhydroxide. f) Energy barrier profiles of different reaction steps in NiCuFe oxyhydroxide and NiCu oxyhydroxide via pathway II. Charge difference g) in NiCu oxyhydroxide system, and h) NiCuFe oxyhydroxide. Reproduced with permission. [221] Copyright 2021, Wiley-VCH. i) Performance comparison of sulfide oxidation and OER catalyzed by CoNi@NGs. j) Photo of the H 2 S electrolysis device driven by a 1.2 V commercial battery directly. k) FE and H 2 evolution rates in a galvanostatic test at 100 mA cm −2 . l) Comparison of the projected density of states of S(3p) and its bonded C(2p) when S is adsorbed on the surface of pristine graphene, CoNi@Gs and CoNi@NGs. m) Free energy profiles of the formation of polysulfides (S x *) in the aqueous solution on N-Graphene's surface and CoNi@NGs' surface. Reproduced with permission. [222]

Dual CoxSy-Modified Tungsten Disulfide Double-Heterojunction Electrocatalyst for Efficient Hydrogen Evolution in All-pH Media

“…Driven by the exhaustion of fossil energy and the changing climate, developing sustainable and renewable clean energy sources requires unremitting efforts from the scientific community. Intermittent wind and solar energy are used for driving the electrocatalytic hydrogen evolution reaction (HER) to produce hydrogen (H 2 ) with low carbon footprint and high energy density, which has remarkable significance for mitigating energy challenges. − The HER process has been well recognized in industry, mainly including Volmer (H + + M + e – → M – H* in acidic electrolytes and H 2 O + M + e – → M – H* + OH – in alkaline or neutral electrolytes), Heyrovsky (M – H* + H + + e – → M + H 2 in acidic electrolytes and M – H* + H 2 O + e – → M + OH – + H 2 in alkaline or neutral electrolytes), and Tafel (2M – H* → 2M + H 2 ) types. , The surface coverage of adsorbed hydrogen atoms (H ads ) can be considered as the reactive intermediate for HER to undergo Volmer–Heyrovsky (low H ads coverage) or Volmer–Tafel (high H ads coverage) . Currently, Pt-based electrocatalysts have been extensively studied and served as benchmarks for HER electrocatalysts due to their high H ads coverage. , However, the high price and limited reserve prevent their widespread commercialization.…”

“…1−3 The HER process has been well recognized in industry, mainly including Volmer (H + + M + e − → M − H* in acidic electrolytes and H 2 O + M + e − → M − H* + OH − in alkaline or neutral electrolytes), Heyrovsky (M − H* + H + + e − → M + H 2 in acidic electrolytes and M − H* + H 2 O + e − → M + OH − + H 2 in alkaline or neutral electrolytes), and Tafel (2M − H* → 2M + H 2 ) types. 4,5 The surface coverage of adsorbed hydrogen atoms (H ads ) can be considered as the reactive intermediate for HER to undergo Volmer−Heyrovsky (low H ads coverage) or Volmer−Tafel (high H ads coverage). 6 Currently, Pt-based electrocatalysts have been extensively studied and served as benchmarks for HER electrocatalysts due to their high H ads coverage.…”

Hollow Mo-doped NiSx nanoarrays decorated with NiFe layered double-hydroxides for efficient and stable overall water splitting

“…1 Hydrogen energy, as a clean and high energy density source, is considered to be a perfect substitute for traditional fossil energies. [2][3][4] Compared with traditional hydrogen production methods, electrocatalytic water splitting has elicited research interest owing to its simple operation and environment-friendly products. 5,6 Water electrolysis comprises two half-reactions, the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), 7,8 but the high potential and slow kinetics of the OER reduce the overall efficiency of water splitting, which encourages us to design more HER/OER catalysts with low overpotential.…”

Facile surface reconstructions of cobalt–copper phosphide heterostructures enable efficient electrocatalytic glycerol oxidation for energy-saving hydrogen evolution

“…By doing so, the overall voltage input for hydrogen evolution can be reduced significantly, the possible formation of an explosive O 2 /H 2 gas mixture is avoided, and valuable chemicals are co-produced to further reduce the potential cost. [22][23][24][25][26][27][28] Among the various small organic molecules, glycerol stands out as an attractive economically viable feedstock to assist the hydrogen evolution reaction (HER) due to several reasons: (1) glycerol oxidation reaction (GOR) requires a significantly lower thermodynamic oxidation potential (0.003 V vs. reversible hydrogen electrode, RHE) compared to the OER (1.23 V vs. RHE); 29 (2) a variety of high value-added products can be generated via selective glycerol oxidation; 30 (3) glycerol is a cheap by-product in over-supply from biodiesel and the soap industry. 31,32 The most effective electrocatalysts for the GOR reported so far are often based on noble metals 33 such as Au, Pd, Pt and their alloys (PtBi and PdBi), 34,35 which suffer from high cost and poor stability against poisoning, making them less competitive for economically feasible hydrogen production.…”

“…By doing so, the overall voltage input for hydrogen evolution can be reduced significantly, the possible formation of an explosive O 2 /H 2 gas mixture is avoided, and valuable chemicals are co-produced to further reduce the potential cost. 22–28…”