Phosphorus-doped porous carbon nitride for efficient sole production of hydrogen peroxide via photocatalytic water splitting with a two-channel pathway

The production of hydrogen peroxide (H2O2) by photocatalytic water splitting has attracted much attention due to the wide application of H2O2 as a multi-functional chemical. Most of the present photocatalysts require sacrificial agents and/or noble metal cocatalysts. Herein, we report that phosphorus-doped porous carbon nitride (CPN), as a metal-free photocatalyst, achieves the photocatalytic water splitting via a two-channel pathway (water oxidation reaction and oxygen reduction reaction) with high H2O2 yield of 1968 μmol g−1 h−1 (highest yield in current records without sacrificial agent) under room temperature and normal pressure without sacrificial agent and cocatalyst. The quantum efficiency of the sole production of H2O2 was measured to be 1.57% under wavelength λ = 420 nm and the solar energy conversion efficiency was determined to be 0.43%. In the present reaction system, the concentration of H2O2 can be up to 0.171% (wt%) in a one-batch reaction using 80 mg CPN catalyst (in 15 mL oxygen saturated H2O) after 36 h under visible light illumination. H2O2 obtained by this metal-free catalyst without adding a sacrificial agent is more conducive to subsequent purification in industrial production.