Synergetic piezo-photocatalysis of g-C3N4/PCN-224 core-shell heterojunctions for ultrahigh H2O2 generation
Hydrogen peroxide(H2O2)is a high-value-added chemical for multitudinous industrial applications.Being compared with traditional anthraquinone processes,it is an eco-friendly and promising strategy to accomplish catalytic reduction of molecular oxygen for H2O2 production with the aid of mechanical and solar energy.It was the first attempt to combine a porphyrin-based metal-organic framework(PCN-224)and piezoelectric semiconductor(g-C3N4)to fabricate heterostructures(ab-breviated as CP-x)with core-shell structure for piezo-photocatalytic H2O2 production.The introduc-tion of PCN-224 not only widened light absorption range and accelerated electron transfer,but also facilitated the hydrogenation and generation of OOH*,which was more prone to direct two-electron O2 reduction.Furthermore,benefitting from the synergism of the piezo-photocatalysis,an excep-tional piezo-photocatalytic H2O2 evolution rate of 5.97 mmol g-1 h-1 with solar-to-chemical conver-sion(SCC)efficiency of 0.14％was achieved by the optimum CP-5 heterojunction.This achievement significantly surpassed the previously reported g-C3N4-based and MOF-based materials.The use of rainwater as proton sources also allowed an impressive H2O2 generation rate(2.78 mmol g-1 h-1),thereby this outcome was of great significance to the rainwater utilization.This work contributed an in-depth understanding of piezo-photocatalytic O2 reduction and provided an alternative way for the development of porphyrinic MOFs heterojunctions for synthesis of H2O2.
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