Template-Free Synthesis of Zinc Cobalt Oxides/Phosphides (Co2P/CoO/ZnCo2O4) Hollow Sub-Micron Boxes as Hydrogen Evolution Reaction Catalysts

In this work, we report the template-free synthesis of zinc cobalt oxides/phosphides (Co2P/CoO/ZnCo2O4) hollow sub-micron boxes as electrocatalysts for HER (hydrogen evolution reaction). The synthesis of such sub-micron box starts with the preparation of the hollow oxide sub-micron box and is followed by a phosphorization process. It is proven that the selective etching induces by cation exchange (Zn2+ and Co2+) was the key to the formation of the hollow structure. The analysis of chemical states and electrochemical activity further reveals Zn enhanced the intrinsic activity of catalysts by increasing the electron density of Co in final products. The optimized ZnCo-OP hollow sub-micron box exhibits good HER activity with overpotentials of 112 mV at 10 mA/cm(2) and 197 mV at 250 mA/cm(2).

Automated summary

This study presents a template-free synthesis of zinc cobalt oxides/phosphides hollow sub-micron boxes as electrocatalysts for the hydrogen evolution reaction. The selective etching induced by cation exchange plays a key role in forming the hollow structure, while the addition of zinc enhances the intrinsic activity of the catalysts. The optimized ZnCo-OP hollow sub-micron box exhibits good hydrogen evolution reaction activity with low overpotentials.