(578h) Electrochemical Synthesis of Hydrogen Peroxide from Two-Electron Water Oxidation

Samira Siahrostami^[1], Guo-Ling Li,^[2],[3] Xinjian Shi,^[4] Xiaolin Zheng,^[4] Jens K. Nørskov^[1],[2]

 samiras@stanford.edu

[1] SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, 443 Via Ortega, Stanford, California 94305, United States

[2] SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States

[3] School of Physics and Engineering, Henan University of Science and Technology, Luoyang 471023, China

[4] Department of Mechanical Engineering, Stanford University, 443 Via Ortega, Stanford, California 94305, United States

Hydrogen peroxide (H₂O₂), known as a green and sustainable solvent, is one of top 100 most important chemicals in the world. Hydrogen peroxide has wide applications such as in paper industry, textile industry and detoxification and color removal for wastewater.¹ The wastewater treatment application is of particular interest because only less than 1% of water resources on earth are accessible for human usages. Frequently, pollutants from urban, industrial, and agricultural human activities contaminate these available water resources. Majority of these pollutants are only be oxidized into harmless products without generating waste in water by hydrogen peroxide. In contrast to adding H₂O₂ to water, it is very attractive to directly convert water to H₂O₂ on a photoanode (eq. 1) using sunlight, and to evolve hydrogen gas (H₂) (eq. 2) on the photocathode. Such system provides a clean process to produce two valuable chemicals: hydrogen gas and hydrogen peroxide (eq. 3) while purifying the water.

2H₂O --> H₂O₂ + 2(H⁺+e^-) E⁰=-1.76 V (1)

2(H⁺+e^-) --> H_2  E⁰=0.0 V (2)

2H₂O --> H₂O₂ + H_2 (3)

In this work, we use combined density functional theory (DFT) and experiments to identify suitable photoanodes that have high selectivity towards two-electron path (H₂O₂ evolution), instead of four-electron path (O₂ evolution). Our DFT calculations suggest BiVO₄ as one of the best and most active catalyst for H₂O₂ production (Eq. 1). This is confirmed by our experimental results that show BiVO₄ has high faraday efficiency about 60% at 2.0 V vs. RHE towards hydrogen peroxide evolution.

References

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(5) Fuku, K.; Sayama, K. Chem. Commun. (Camb). 2016, 52 (31), 5406â??5409.