Synergistic effect of the valence bond environment and exposed crystal facets of the TiO2/SnS2 heterojunction for achieving enhanced electrocatalytic oxygen evolution

Abstract

Cost-effective and high-performance electrocatalysts are vital factors that affect the development of the oxygen evolution reaction (OER). Herein, SnS₂ nanosheets (SnS₂ NSs)-modified TiO₂ nanobelts (TiO₂ NBs) (TiO₂/SnS₂) electrocatalyst with significant enhancement of the OER activity was successfully synthesized by the hydrothermal method. This was achieved by taking advantage of the fast radial transfer of the one-dimensional (1-D) TiO₂ NBs, large areas of contact with the electrolyte and the stability of the two-dimensional (2-D) SnS₂ NSs. The experimental results indicate that the change in the valence bond environment due to the formation of the heterojunction and the independent exposed crystal facets could distinctly reduce the charge-transfer resistance and the adsorption barrier of the H₂O molecules in electrocatalytic water splitting, which are favourable for improving the OER activity. The synergistic effect of the valence bond environment and exposed crystal facets of the TiO₂/SnS₂ heterojunction catalyst have led to remarkable OER performance with an overpotential of 570 mV at the current density of 10 mA cm⁻², a low Tafel slope of 107 mV dec⁻¹ and long-time durability in alkaline solution. This non-precious TiO₂/SnS₂ heterojunction catalyst was designed based on the concept of combining valance factors and crystal facet engineering, which sheds light on a new pathway for the design of new, promising and highly efficient OER electrocatalysts.