Local Photothermal Effect Enabling Ni₃ Bi₂ S₂ 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 (Ni₃ Bi₂ S₂ @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 Ni₃ Bi₂ S₂ as well as the synergistic effect with hierarchical configuration, upon injecting the light, the as-prepared Ni₃ Bi₂ S₂ 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 Ni₃ Bi₂ S₂ @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.