Local Photothermal Effect Enabling Ni3 Bi2 S2 Nanoarray Efficient Water Electrolysis at Large Current Density.

ABSTRACT

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.