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

Abstract

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.