Cu2O nanoparticles modified BiO2-x nanosheets for efficient electrochemical reduction of nitrate-N and nitrobenzene from wastewater

Nitrogen-polluted wastewater posed great threat to the environment and human beings. Bismuth-based materials have presented high potentials for wastewater treatment. However, it suffers from unsatisfactory electrocatalytic efficiency, especially for nitrate-N removal. Considering the superior performance of copper in electrochemical reduction reactions, Cu2O nanoparticles modified BiO2-x nanosheets (Cu2O NPs/BiO2-x NSs) were designed and synthesized through a one-step hydrothermal method for wastewater purification. The obtained Cu2O NPs/BiO2-x NSs presents enhanced electrocatalytic activity towards nitrate removing, since the introduced Cu2O NPs not only increased the active sites but also decreased the electrical resistance. The effect of reaction parameters (current density, initial concentration, initial pH, supporting electrolyte, and dissolved oxygen) was also studied to optimize the operation conditions. Meanwhile, the electrochemical and scavenging experiments illustrated the mechanism that both the direct electron transfer and atomic H* played important roles in nitrate reduction. Furthermore, when applying Cu2O NPs/BiO2-x NSs for the treatment of nitrobenzene (NB), it achieved nearly 90% removal efficiency of NB in 30 min. Therefore, the designed Cu2O NPs/BiO2-x NSs shows a wide range of potential for removing both nitroaromatic and inorganic nitrogen pollutants.