Efficient production of H2O2 on Au/WO3 under visible light and the influencing factors

Production of H 2 O 2 via a more economic, green and safe way is challenging. In this work, we report an efficient production of H 2 O 2 from oxygen reduction reaction (ORR) in aqueous solution over a modified WO 3 with Au nanoparticles . Under visible light at wavelengths longer than 420 nm for 5 h, H 2 O 2 measured from WO 3 and Au/WO 3 were 1.07, and 177 μM, respectively. On addition of methanol, H 2 O 2 obtained from WO 3 , Au/WO 3 , and Au/SiO 2 were 8.55, 544, and 0.36 μM, respectively. Photoluminescence and electrochemical measurement revealed that there was an interfacial electron transfer from the excited WO 3 to Au, followed by two-electron reduction of O 2 on Au sites. Under visible light at wavelengths longer than 535 nm, interestingly, H 2 O 2 was also produced from Au/WO 3 (39 μM at 5 h), while the photocurrent of water oxidation on Au/WO 3 was much larger than those on Au/SiO 2 and WO 3 . Clearly, there is also an interfacial electron transfer from the plasmonic Au to WO 3 , followed by ORR to H 2 O 2 , but such a process fails when WO 3 is excited. However, the production of H 2 O 2 on Au/WO 3 was determined by several factors, including Au content, light absorption, and particle size. A maximum H 2 O 2 was observed at an initial pH 3.0 from 0.35 wt% Au/WO 3 , prepared at 400 °C. Moreover, at the same loading on WO 3 , Au was more efficient than Pd, Ag, Pt, Ni, Cu, and Co, while at the same Au loading, WO 3 was more efficient than BiVO 4 and Bi 2 WO 6 . The superior performance of Au/WO 3 is mainly due to its ability to undergo selective ORR to H 2 O 2 , and to release protons into aqueous solution protecting H 2 O 2 from decomposition.