Boosting hydrogen production in ultrathin birnessite nanosheet arrays-based electrolytic cell by glycerol and urea oxidation reactions

It is still a big challenge to develop an innovative strategy to overcome sluggish oxygen evolution reaction (OER). Herein, ultrathin [email protected] foam nanosheet array ([email protected]) with oxygen vacancy (VO) is prepared by an in-situ growth method. [email protected] shows a high activity for water splitting because VO and Mn3+ favor the adsorption of OH− and H2O. Furthermore, glycerol oxidation reaction (GOR) and urea oxidation reaction (UOR) are employed to substitute for OER to improve hydrogen evolution reaction (HER). Compared with OER, the anodic current densities of GOR and UOR have increased by 19.34 and 18.04 times at 1.43 V (vs. reverse hydrogen electrode (RHE)), respectively. To reach the same current density of 30 mA/cm2, the required cell voltages for UOR- and GOR-based electrolytic cells have decreased by about 16% than that of water-based electrolytic cell (2.024 V), meaning that to produce the same amount of hydrogen, about 16% of electric energy can be economized. Besides, the Faradaic efficiencies of UOR- and GOR-based electrolytic cells (95% and 97%) are higher than that of water-based electrolytic cell (92%), confirming a higher conversion of energy. The innovative system can not only produce hydrogen efficiently, but also effectively degrade environmental pollutants.