Achieving simultaneous hydrogen evolution and organic pollutants degradation through the modification of Ag3PO4 using Cs2AgBiBr6 quantum dots and graphene hydrogel

Abstract

The Ag3PO4/Cs2AgBiBr6 quantum dots/graphene hydrogel (ACGH) photocatalytic system was designed. The Cs2AgBiBr6 quantum dots (CABBQDs) and graphene hydrogel (rGH) solved the insufficient redox ability and easy photocorrosion of Ag3PO4, at the same time, the novel system achieved full-spectrum-driven photoreforming to use for efficient photocatalytic hydrogen evolution and simultaneous organic compounds photodegradation. The feasibility study of alternative sacrificial agents evaluated higher simultaneous photocatalytic activity in tetracycline hydrochloride (TC) compared to general sacrificial agents (methanol, Na2S/Na2SO3, acid orange and glucose). The yield of hydrogen production and simultaneous photodegradation efficiency of TC were 5965.8 μmol/g and 98.32 % respectively in 6 h. And the hydrogen production rate in TC solution was more than twice that of general sacrificial agents within 24 h. Meanwhile, the mechanism exploration elucidated the photogenerated charge transfer path to generate the water splitting and photoinduced oxidizing species (h+, OH, ·O2-). The Hirshfeld atomic charges on TC and methanol molecules were calculated by density functional theory to predict the initial attack sites. Results indicated that the CCO and CNC fragments on TC molecules were inferred as nucleophilic attack and radical attack sites. And more electrons on TC could give to ACGH constantly for hydrogen production than methanol. The yield of hydrogen production and simultaneous degradation efficiency of TC remained at 3683.24 μmol/g and 93.22 % respectively in six photocatalytic cycle experiments, showing the reusability of ACGH. The simultaneous hydrogen production and degradation of organic pollutants of ACGH could proceed in actual municipal wastewater.