Coupling Glucose-Assisted Cu(I)/Cu(II) Redox with Electrochemical Hydrogen Production

Water electrolysis is a sustainable technology for hydrogen production since this process can utilize the intermittent electricity generated by renewable energy such as solar, wind, and hydro. However, the large-scale application of this process is restricted by the high electricity consumption due to the large potential gap (>1.23 V) between the anodic oxygen evolution reaction and the cathodic hydrogen evolution reaction (HER). Herein, a novel and efficient hydrogen production system is developed for coupling glucose-assisted Cu(I)/Cu(II) redox with HER. The onset potential of the electrooxidation of Cu(I) to Cu(II) is as low as 0.7 V_RHE (vs reversible hydrogen electrode). In situ Raman spectroscopy, ex situ X-ray photoelectron spectroscopy, and density functional theory calculation demonstrates that glucose in the electrolyte can reduce the Cu(II) into Cu(I) instantaneously via a thermocatalysis process, thus completing the cycle of Cu(I)/Cu(II) redox. The assembled electrolyzer only requires a voltage input of 0.92 V to achieve a current density of 100 mA cm^-2 . Consequently, the electricity consumption for per cubic H₂ produced in the system is 2.2 kWh, only half of the value for conventional water electrolysis (4.5 kWh). This work provides a promising strategy for the low-cost, efficient production of high-purity H₂ .