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 MoS2、TiO2、MoS2@TiO2 and TiO2@MoS2 sensors are 18.7, 39.8, 3905 and 207 respectively.