Local Photothermal Effect Enabling Ni3Bi2S2 Nanoarray Efficient Water Electrolysis at Large Current Density

In terms of the large-scale hydrogen production by water electrolysis, achieving the bifunctional electrocatalyst with high efficiency and stability at high current densities is of great significance but still remains a grand challenge. To address this issue, herein, one unique hybrid electrode is synthesized with the local photothermal effect (LPTE) by supporting the novel ternary nickel (Ni)  bismuth (Bi)  sulfur (S) nanosheet arrays onto nickel foam (Ni 3 Bi 2 S 2 @NF) via a one-pot hydrothermal reaction. The combined experimental and theoretical observations reveal that owing to the intrinsic LPTE action of Bi, robust phase stability of Ni 3 Bi 2 S 2 as well as the synergistic effect with hierarchical configuration, upon injecting the light, the as-prepared Ni 3 Bi 2 S 2 exhibits remarkably improved efficiency of 44% and 35% for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Such enhanced values are also comparable to those performed in working media heated to 80 °C. In addition, the overall water splitting system by using Ni 3 Bi 2 S 2 @NF as bifunctional electrodes only delivers an ultralow voltage of 1.40 V at 10 mA cm −2 under LPTE, and can be stable more than 36 h at 500–1000 mA cm −2 . More broadly, even worked at 0–5 °C, alkaline simulated seawater and high salt seawater, the electrodes still show apparent LPTE effect for improving catalytic efficiency.