Photoenhanced Water Electrolysis in Separate O₂ and H₂ Cells Using Pseudocapacitive Electrodes

Abstract

Water electrolysis has received much attention in recent years as a means of sustainable H 2 production. However, many challenges remain in obtaining high-purity H 2 and making large-scale production costeffective. This study provides a strategy for integrating a two-cell water electrolysis system with solar energy storage. In our proposed system, CuO-Cu(OH) 2 /Cu 2 O was used as a redox mediator between oxygen and hydrogen evolution components. The system not only overcame the gasmixing issue but also showed high gas generation performance. The redox reaction (charge/discharge) of CuO-Cu(OH) 2 /Cu 2 O led to a significant increase (51%) in the initial rate of H 2 production from 111.7 μmol h −1 cm −2 in the dark to 168.9 μmol h −1 cm −2 under solar irradiation. The effects of light on the redox reaction of CuO-Cu(OH) 2 /Cu 2 O during water electrolysis were investigated by in situ X-ray absorption and photoemission spectroscopy. These results suggest that surface oxygen vacancies are created under irradiation and play an important role in increased capacitance and gas generation. These findings provide a new path to direct storage of abundant solar energy and low-cost sustainable hydrogen production.

John Stuart Mill, Socialist

“…In addition to Ni(OH) 2 , NaMnO 2 and organics as redox electrodes, other some redox electrodes were also used, such as the (Ni 5 Mn) 2 P on nickel foams [89], CuO/Cu 2 O [90], polyaniline [91] and NaTi 2 (PO 4 ) 3 [92] electrodes. The former two works stated that the materials showed the pseudocapacitive behaviours which in fact were Nerst characteristic peaks in CVs.…”

Half-Electrolysis of Water with the Aid of a Supercapacitor Electrode

“…In 2013, decoupling HER and OER during the electrolysis of water was realized with a phosphomolybdic acid . Since 2016, separations of HER and OER had been developed in the electro- and photoelectron water splitting without the membranes by faradaic reaction solid electrodes. − In 2014, half-electrolysis was demonstrated to run a desirable half-cell reaction on an electrolysis electrode with the aid of a counter supercapacitor electrode, which only experienced charging and discharging, eliminating the other unwanted but inevitable half-cell reaction in conventional electrolysis. Typically, OER, even possible chlorine evolution reaction (ClER), for seawater electrolysis is not as important as HER for the hydrogen economy.…”