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 hetero-structure 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 H-2 production. Once BP is added to TiO2 (P25) as only 1% wt., the H-2 evolution rate increases up to 4 times reaching a value of 830 mu mol/g center dot h under UV-Vis light irradiation. By integrating CoP nanoparticles as a cocatalyst up to 2% wt., H-2 production is further promoted to 7400 mu mol/g center dot 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.