MoS₂ compounded bidirectionally with TiO₂ for hydrogen evolution reaction with enhanced humidity sensing performance

A proper catalyst is the key factory for hydrogen evolution reaction (HER). Both MoS₂ and TiO₂ are regarded as potential candidates for HER, because MoS₂ possesses a large number of active edge site and TiO₂ has hydrophobic with special structure. In this work, MoS₂ and TiO₂ are compounded bidirectionally for unique morphology by two-step hydrothermal method. The hydrogen evolution properties of two kinds of subsequent composites are studied for the first time. The active sites for HER of the two composite catalysts are increased greatly after compounding, so is their specific surface area. As a result, the Tafel slope of TiO₂@MoS₂ and MoS₂@TiO₂ are reduced to 70.6 mV/dec and 60.5 mV/dec respectively. At 200 mV over-potential, the density of MoS₂@TiO₂ is 7.6 mA/cm² raised by 15.2 times than MoS₂, while that of TiO₂@MoS₂ is 2.2 mA/cm² promoted by 7 times than TiO₂. The enhanced specific surface area also improved the humidity properties of the two compounds with the rangeability of impedance raising two orders. The sensibility of MoS_2、TiO_2、MoS₂@TiO₂ and TiO₂@MoS₂ sensors are 18.7, 39.8, 3905 and 207 respectively.