Electronic modulation of NiS-PBA/CNT with boosted water oxidation performance realized by a rapid microwave-assisted in-situ partial sulfidation

Hydrogen is considered as the promising renewable resources in future C-free systems, but more efficient and scalable synthesis is required to enable its widespread deployment. Here, in-situ generated hierarchical NiS-PBA/ CNT hybrid has been fabricated which combined the high conductivity and electrocatalytic activity together. Through study the electronic structure, it was found that the electron transfer among metal atom enable higher activity. The optimized NiS-PBA/CNT delivers an ultralow overpotential of 253 mV @ 20 mA cm-2, a small Tafel slope of 49.8 mV dec-1, and can work steadily for more than 40 h with a Faradic efficiency of 95.5%. Density functional theory calculations based on the NiS-PBA, NiS and PBA model reveal that the enhanced catalytic activities of NiS-PBA is mainly manifested in its lower free energy of rate-determining step (the oxidation of *OH to *O) and higher electrical conductivity. This work provides a novel partial sulfidation strategy for PBA to significantly boost catalytic performance. And the microwave-assisted solvothermal reaction offers a novel mild implementation toward in situ heterogeneous doping for carbon matrix.

Automated summary

A hierarchical NiS-PBA/CNT hybrid with high conductivity and electrocatalytic activity was fabricated, showing ultralow overpotential, small Tafel slope, and high Faradic efficiency. The enhanced catalytic activity of NiS-PBA is attributed to its lower free energy and higher electrical conductivity, as revealed by density functional theory calculations. The study provides a novel partial sulfidation strategy for enhancing catalytic performance and a mild approach for in situ heterogeneous doping in carbon matrices through microwave-assisted solvothermal reaction.