Self-Driven Salt-Thermal Reduction Approach for the Synthesis of Cu2O and AgCl–Cu2O Hybrids with Superior Photocatalytic Activity

High-temperature molten salts are excellent solvents for materials synthesis, because they not only provide a water- and oxygen-free environment but also accelerate the reaction rate by enhancing the mass/electron transport in a liquid medium. Herein, a self-driven salt-thermal reduction approach is reported for preparing low-valence oxides and their compounds without using any reducing agent or toxic chemical. The molten-salt medium drives the reduction of oxides to suboxides and oxygen (e.g., from CuO to Cu2O) and acts as a capping agent to prevent the growth of oxides. At the same time, the AgCl–Cu2O hybrid is prepared from microsized CuO and AgCl. The prepared AgCl–Cu2O hybrids show superior visible-light photocatalytic activity toward the photodegradation of methyl orange in 10 min with a degradation rate of up to 98.4%. Besides the AgCl–Cu2O hybrid, a library of metal oxides can be prepared using eco-friendly feedstocks and chemicals.