S-Doped Ni(OH)2 nano-electrocatalyst confined in semiconductor zeolite with enhanced oxygen evolution activity†
Low-cost Ni(OH)2-based nanomaterials with various structures and morphologies are promising catalysts for efficient oxygen evolution reactions (OERs). However, homogenous Ni(OH)2 nanomaterials with abundant active sites suffer from low conductivity and easy aggregation, resulting in low catalytic activity and stability. Here, we report a new synthetic method capable of generating abundant and confined S-doped β-Ni(OH)2 nanoparticles (NPs) (3–5 nm) within a 3D semiconductor substrate, metal-chalcogenide semiconductor zeolite (CSZ). This method operates via sequential fluoride-assisted cationic stripping and in situ Ni(OH)2 generation and is demonstrated here as an effective method to synthesize Ni2+-containing CSZ that are known to defy direct synthesis. The resulting composite (denoted Ni(OH)2 NPs@CSZ) exhibited excellent OER performance with a very low overpotential of only 212 mV at a current density of 10 mA cm−2 in O2-saturated 1 M KOH solution, and low Tafel slope of 64.2 mV dec−1, which is superior to that of benchmark IrO2. DFT calculations indicate that the interaction between the embedded Ni(OH)2 NPs and the dopant, S2−, from the host CSZ played a crucial role in improving OER performance. This work provides a new path for developing high-performance Ni(OH)2-based OER catalysts and may also serve as a general approach for loading large amounts of other catalytically active NPs into semiconducting open frameworks to further optimize electrocatalytic performance.