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 gamma-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 gamma-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 gamma-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(-1) g(-1), outperformed the reported traditional photocatalytic syntheses of H2O2.

Automated summary

This research demonstrates a method for generating hydrogen peroxide using sunlight to power selective 2e(-) ORR, with a high selectivity and yield of H2O2. The synthesized N-doped gamma-graphyne catalyst showed superior performance compared to traditional photocatalytic methods for H2O2 synthesis.