Engineering thiospinel-based hollow heterostructured nanoarrays for boosting electrocatalytic oxygen evolution reaction

Thiospinels, members of the spinel family, have been demonstrated to be promising for boosting the electrocatalytic oxygen evolution reaction (OER), but their practical application is severely impeded by limited catalytically active sites and low intrinsic activity. Geometric configuration and electronic structure engineering have been demonstrated to play a paramount role in improving the electrocatalytic OER. However, there are few reports targeting thiospinel-based electrocatalysts that simultaneously employ these two strategies. Herein, we have designed a well-controlled hollow heterostructure of NiS/NiCoS with rich heterointerfaces through a facile hydrothermal method. Benefitting from the hollow nanotube structure, the NiS/NiCoS catalyst can expose more catalytically active sites accessible to reactants and intermediates as well as provide more routes for facilitating electron transfer. Moreover, the unique heterostructure greatly modifies the electronic structure and generates lattice strain at the heterojunction interface to optimize the binding strength with intermediate species. As a result, NiS/NiCoS exhibited markedly high OER activity, achieving a current density of 100 mA cm with an overpotential of 177 mV and maintaining high stability during a 200 h test.