Z-Scheme Ba2AgIO6/C3N4 Heterojunction Enabling Efficient Visible-Light Photocatalytic H2O2 Production via Direct One-Step Two-Electron O2 Reduction Reaction

Abstract

The photocatalytic direct one-step two-electron (2e-) oxygen reduction reaction (ORR) holds great potential in efficient H2O2 synthesis. However, it is still a significant challenge to design photocatalysts for achieving high-efficiency H2O2 production via this direct one-step 2e- ORR pathway. To address this, we have constructed a Z-scheme BAIO/C3N4 heterojunction by in situ growing Ba2AgIO6 (BAIO) on the surface of C3N4 nanosheets. Under visible light irradiation, the optimal sample, with a BAIO:C3N4 mass ratio of 1:1.5, exhibited a remarkable H2O2 yield of up to 535.9 μmol g-1 h-1, which is 8.8 times higher than that of pure C3N4. This enhancement is attributed to the improved charge separation and migration efficiency facilitated by the enhanced internal electric field (IEF) in BAIO/C3N4 heterojunction. Furthermore, the heterojunction altered the O2 adsorption configuration to the Yeager-type, promoting a more efficient and selective direct one-step 2e- ORR for H2O2 production. This study highlights the importance of regulating the reaction pathway to enhance photocatalytic H2O2 production activity and offers a new insight for designing highly active photocatalysts.