Bias-free synthesis of hydrogen peroxide from photo-driven oxygen reduction reaction using N-doped γ-graphyne catalyst

It is an ideal route to generate hydrogen peroxide (H2O2) via selective 2e- ORR powered directly by sunlight. In this work, we synthesized a metal-free N-doped γ-graphyne catalyst and wired it with n-type semiconductor photoanodes. The introduction of sunlight could lower the onset bias of oxygen reduction reaction (ORR) up to 0.32 V and H2O2 was steadily produced without any sacrificial agents and bias. The 2e- ORR selectivity of N-doped γ-graphyne catalyst was bias dependent, and it reached about 74% at 0 bias in 0.1 mol·L−1 KOH. Theoretical calculations showed that in-situ pyridinic-N in N-doped γ-graphyne acted as the active site for ORR, accelerating the rate-determining step of proton abstraction. The H2O2 yield reached as high as 7.47 mmol·h−1g−1, outperformed the reported traditional photocatalytic syntheses of H2O2.