Selective electrochemical generation of hydrogen peroxide from water oxidation

TL;DR

This paper proposes a decentralized sunlight-driven device for water splitting that selectively produces hydrogen peroxide and hydrogen, using a new electrocatalyst screening method based on density functional theory.

Contribution

It introduces a rational design principle for electrocatalysts that selectively produce hydrogen peroxide during water oxidation, supported by theoretical screening of materials.

Findings

SnO₂ can activate hydrogen peroxide evolution.

Density functional theory can predict selectivity trends.

New material candidates for H₂O₂ production identified.

Abstract

Water is a life-giving source, fundamental to human existence, yet, over a billion people lack access to clean drinking water. Present techniques for water treatment such as piped, treated water rely on time and resource intensive centralized solutions. In this work, we propose a decentralized device concept that can utilize sunlight to split water into hydrogen and hydrogen peroxide. The hydrogen peroxide can oxidize organics while the hydrogen bubbles out. In enabling this device, we require an electrocatalyst that can oxidize water while suppressing the thermodynamically favored oxygen evolution and form hydrogen peroxide. Using density functional theory calculations, we show that the free energy of adsorbed OH$^*$ can be used as a descriptor to screen for selectivity trends between the 2e$^-$ water oxidation to H$_2$O$_2$ and the 4e$^-$ oxidation to O$_2$. We show that materials that bind oxygen intermediates sufficiently weakly, such as SnO$_2$, can activate hydrogen peroxide evolution. We present a rational design principle for the selectivity in electrochemical water oxidation and identify new material candidates that could perform H$_2$O$_2$ evolution selectively.