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.