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

Abstract 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 H 2 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 H 2 .