Review of the methods to form hydrogen peroxide in electrical discharge plasma with liquid water

TLDR

Plasma processes ranging from rf to pulsed, ac, and dc discharges in liquid phase exhibit similar energy yields, suggesting that radical quenching at the plasma–liquid interface limits performance. This review surveys the literature on hydrogen peroxide formation from plasma processes. The review highlights that the most efficient plasma approach employs liquid water droplets, which sequester hydrogen peroxide and suppress radical‑induced decomposition at the gas–liquid interface. Reported energy yields for plasma‑generated hydrogen peroxide span 0.04–80 g kWh⁻¹, bubble or surface discharges offer modest gains but are complicated by gas‑phase chemistry, kinetic models predict up to 45 % of the thermodynamic limit, and direct plasma from water outperforms electron‑beam, ultrasound, electrochemical, photochemical, and other chemical methods.

Abstract

This paper presents a review of the literature dealing with the formation of hydrogen peroxide from plasma processes. Energy yields for hydrogen peroxide generation by plasma from water span approximately three orders of magnitude from 4 × 10−2 to 80 g kWh−1. A wide range of plasma processes from rf to pulsed, ac, and dc discharges directly in the liquid phase have similar energy yields and may thus be limited by radical quenching processes at the plasma–liquid interface. Reactor modification using discharges in bubbles and discharges over the liquid phase can provide modest improvements in energy yield over direct discharge in the liquid, but the interpretation is complicated by additional chemical reactions of gas phase components such as ozone and nitrogen oxides. The highest efficiency plasma process utilizes liquid water droplets that may enhance efficiency by sequestering hydrogen peroxide in the liquid and by suppressing decomposition reactions by radicals from the gas and at the interface. Kinetic simulations of water vapor reported in the literature suggest that plasma generation of hydrogen peroxide should approach 45% of the thermodynamics limit, and this fact coupled with experimental studies demonstrating improvements with the presence of the condensed liquid phase suggest that further improvements in energy yield may be possible. Plasma generation of hydrogen peroxide directly from water compares favorably with a number of other methods including electron beam, ultrasound, electrochemical and photochemical methods, and other chemical processes.