Surface reconstruction through cathodic activation of first-row transition metal phosphides for enhanced hydrogen evolution

Abstract

The hydrogen evolution reaction (HER) strongly depends on the electronic structure and local microstructures of active sites on the real catalytic surface. Here, we propose a catalytic surface reconstruction approach through cathodic activation to concurrently regulate the electronic configuration and surface microstructure on 1^st-row transition metal (Co, Ni and Fe) phosphides and further boost activity through element integration. The surface reconstruction of V-doped CoP nanowires is realized by cathodic activation, which lowers chemical valence and rearranges the electronic distribution of Co sites for higher intrinsic HER activity, as revealed by synchrotron X-ray absorption spectroscopy. Meanwhile, the microstructure disorder including crystalline expansion, distortion and defects can provide extra catalytic sites for the HER. V incorporation amplifies the above promotion effect by electronic interaction with Co and promoting microstructure disorder. The activated V-doped CoP exhibits 2-fold higher current density than pristine CoP at an overpotential of 100 mV and demonstrates an excellent pH-universal activity.