Efficient Hydrogen Peroxide (H 2 O 2 ) Synthesis by CaSnO 3 via Two-Electron Water Oxidation Reaction

Electrochemical in situ hydrogen peroxide (H 2 O 2 ) generation from a two-electron water oxidation reaction (2e-WOR) is a challenge, not only on catalyst selection but also on electrode making. Herein, the H 2 O 2 electrocatalyst CaSnO 3 nanoparticles were prepared by low-cost glucose as an agent and characterized by X-ray diffraction (XRD), thermogravimetric and differential scanning calorimetry (TG-DSC), Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The active sites for the OH – adsorption on the surface CaSnO 3 (121) was identified by density functional theory (DFT) calculation, and the corresponding reaction mechanism of H 2 O 2 formation was proposed. The CaSnO 3 nanoparticles can be formed from 650 to 850 °C, and the particle sizes are in the range of 27.2–37.3 nm. The mechanism of catalyst formation is that species of Ca and Sn reacted with oxygen to generate CaO and SnO 2 during low-temperature calcination and CaSnO 3 generated during high-temperature calcination. The active sites are the coordination-unsaturated Sn ions, which easily adsorb the negative-charge OH – from the solution, forming an OH* intermediate, and two adsorbed OH* can combine to generate a neutral H 2 O 2 molecule. The H 2 O 2 generation rate over CaSnO 3 was calcinated at 850 °C is 347.7 μmol·min –1 ·g –1 at 2.6 V versus Ag/AgCl under dark conditions. The work opens an in situ H 2 O 2 generation route, direct water oxidation, with wide application prospects.