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Asymmetric electrodes with a transition metal disulfide heterostructure and amorphous bimetallic hydroxide for effective alkaline water electrolysis

Wang, Xiao Hu, Ling, Yu, Li, Bang Lin, Li, Xiao Lin, Chen, Guo, Tao, Bai Xiang, Li, Ling Jie, Li, Nian Bing, Luo, Hong Qun
Journal of materials chemistry A 2019 v.7 no.6 pp. 2895-2900
active sites, alkalinity, anodes, catalysts, cathodes, durability, electric potential difference, electrolysis, hydrogen production, iron, molybdenum disulfide, nanosheets, nickel, oxygen production, potassium hydroxide, protons, water
Through hydro- and solvothermal methods and an electrodeposition-assisted in situ growth strategy, a transition metal disulfide (TMD)-assembled heterostructural cathode (Ni₃S₂/MoS₂-CC) and derivative TMD superficial amorphous bimetallic hydroxide-coated anode (NiFe(OH)ₓ@Ni₃S₂/MoS₂-CC) were successfully prepared for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. The synthesized electrodes demonstrate first-rate performance with enhanced durability for electrolysis. Individually, Ni₃S₂/MoS₂-CC affords an overpotential (η) of 173 mV (at 100 mA cm⁻²) in HER, while NiFe(OH)ₓ@Ni₃S₂/MoS₂-CC affords an η of 309 mV (at 100 mA cm⁻²) in OER. Tight interstratification between the nanosheet (NS) array and amorphous bimetallic hydroxides lead to enhanced affinity for OH⁻/H⁺, improved conductivity, increased charge transfer, and enriched active sites. The two-electrode alkaline (1.0 M KOH) electrolyzer (NMC//NFNMC) requires a low overall voltage (ΔV) of 1.55 and 1.71 V to reach 10 and 100 mA cm⁻², respectively. The rational combination of TMDs and TMDs/NiFe(OH)ₓ delivers a useful methodology for designing and constructing low-cost, hierarchical, transition metal-based composite catalysts with high performance for water electrolysis.