Electronic Tuning of SnO2 by rGO Nanosheets for Highly Efficient Photocatalytic Hydrogen Peroxide Evolution

Hydrogen peroxide (H2O2) photocatalytic production from saturated oxygen and water in solar irradiation is an eco-friendly, sustainable, and safe process. Tin dioxide (SnO2) is a promising photocatalyst with excellent light absorption and a low band-gap energy. Reduced graphene oxide (rGO) can promote charge separation and reduce photogenerated charge recombinations. Here, we represent different concentrations of the rGO dopant in SnO2 that enhance the absorption in the visible range and reduce the energy band gap. rGO–SnO2 successfully promotes water oxidation by 2e reduction of O2, producing hydrogen peroxide. Composite materials enhance the H2O2 yield in the presence of an organic electron donor (OED). The catalyst shows excellent endurance under different acidic conditions. Among all concentrations of rGO (0.5, 1, 2, and 4 wt %), 0.5 wt % rGO–SnO2 shows a more efficient H2O2 production in the presence of oxalic acid, as a stabilizer and an organic electron donor. Finally, we affirm a strategy to enhance photocatalytic hydrogen peroxide production regarding charge separation, light absorption, and surface catalytic reaction in an acidic environment. Our work provides valuable guidance to design efficient photocatalysts for H2O2 generation by an insight mechanism.