(Digital Presentation) Interface Engineering of Transition Metal-Selenide Heterostructures for Application in Electrochemical Water-Splitting

Abstract

Transition metal selenides (TMS) have sparked great interest in energy storage and catalysis because they are direct bandgap materials, have a highly layered structure, high redox activity, abundant active sites at the edges, short diffusion paths, and large surface area1. However, low electrical conductivity and structural instability result in long-term performance degradation. The development of high-performance water electrolyzers and metal-air batteries requires the design and construction of efficient TMS electrocatalysts. In order to boost electrochemical activity, increasing emphasis has been devoted to interface engineering of TMS heterostructures through manipulation of composition, adjustment of crystal facets, and heteroatomic doping2. Interface engineering helps in optimizing reaction intermediates, modulating charge carrier characteristics, and preventing the aggregation of active components. Herein, we designed and studied the interface between hydrothermally synthesized tin selenide (SnSe2) and tungsten selenide (WSe2). The intimate electronic interaction between the bimetallic selenides leads to a rich interface boundary that reduces the surface energy and creates a larger number of active sites involved in both the hydrogen evolution and oxygen evolution reactions3. These heterostructures exhibited a low overpotential of 180 mV at 10 mA cm-2 and good stability of up to 12 hours for the hydrogen evolution reaction, and a low overpotential of 250 mV at 10 mA cm-2 and stability up to 12 hours for the oxygen evolution reaction. This study gives a better insight into the design of TMS heterostructures using interface engineering for high electrocatalytic activity.