Photothermocatalytic Hydrogen Evolution over Ni2P/TiO2 for Full Spectrum Solar Energy Conversion

For photocatalytic solar energy conversion, the critical challenge is to enhance the solar utilization efficiency. Many efforts have focused on the development of broad-band response nanomaterials. Here, we propose an alternative approach wherein, over Ni2P/TiO2 nanoparticles without noble metal, the UV-vis part of solar energy was absorbed and converted by a semiconductor and its infrared part was separately collected and converted into thermal energy to heat the photocatalytic reaction to a certain temperature. The photothermocatalytic hydrogen activity was 3.6 times that of the sum of the photocatalytic and thermocatalytic reactions. The in situ generated oxygen vacancies in Ni2P/TiO2 during the photothermocatalytic reaction were found to be responsible for the enhanced activity. Moreover, the photocurrent transient response results revealed the faster transfer of electrons from TiO2 to Ni2P at higher temperature which is vital for the significantly enhanced photothermocatalytic hydrogen production. The long-term test also shows the stability of the proposed reaction system.