Black Phosphorus as Promoter for Noble Metal-Free Photocatalytic Hydrogen Production

Photocatalysts which are stable to photocorrosion and noble metal-free, are highly desirable to achieve a light-driven hydrogen production which satisfies the criteria of low production cost and environmental sustainability. Herein, a new heterostructure TiO2/BP/CoP has been developed, in which the BP nanosheets interact strongly with TiO2 and CoP, speeding up the transfer of photogenerated electrons and thus increasing H2 production. Once BP is added to TiO2 (P25) as only 1%wt., the H2 evolution rate increases up to 4 times reaching a value of 830 μmol/g·h under UV-Vis light irradiation. By integrating CoP nanoparticles as a cocatalyst up to 2%wt., H2 production is further promoted to 7400 μmol/g·h, 37 times higher than pristine TiO2. Photoluminescence and electrochemical impedance measurements show that this heterostructure achieves a much more efficient charge separation and reduction of the internal resistance in comparison to pristine TiO2. Combining these data with UV-Vis diffuse reflectance and Mott-Schottky, a plausible mechanism was proposed.