Bi/BiFe(oxy)hydroxide for sustainable lattice oxygen-boosted electrocatalysis at a practical high current density

• Published in: Applied catalysis. B, Environmental Environmental, 2022-11, Vol.317, p.121685, Article 121685
• Main Authors: Jo, Seunghwan, Park, Woon Bae, Lee, Keon Beom, Choi, Hyeonggeun, Lee, Kug-Seung, Ahn, Docheon, Lee, Young-Woo, Sohn, Kee-Sun, Hong, John, Sohn, Jung Inn
• Format: Article
• Language: English
• Subjects: Bismuth-iron hybridization; DFT calculation; Lattice oxygen mechanism; Oxygen evolution reaction; Practically high current operation
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2022.121685

Lattice oxygen mechanism (LOM) is a promising pathway to circumvent sluggish oxygen evolution reaction (OER) for efficient water electrolysis. The iron (Fe)-based oxyhydroxide materials for OER catalysts by LOM is well known. However, dissolution of Fe atoms and promoting participation level of lattice oxygen at a practical and extremely high current density (> 1000 mA cm-2 for oxygen generation) should be resolved for high performance and long-term stability. Here, controlling the reduction of synthetic intermediates allowed amorphous BiFe (oxy)hydroxides with secondary bismuth (Bi) metal (BM/BiFeOxHy) heterogeneous structures with abundant lattice vacancies to be obtained. The BM/BiFeOxHy electrode exhibited low overpotential of 232 and 359 mV at a current density of 10 and 1000 mA cm-2, respectively. Moreover, the balanced hybridization of Bi/Fe-O was demonstrated to result in long-term catalytic stability without the dissolution of Fe atoms up to 1000 h at the extremely high current density of 1000 mA cm-2 with negligible degradation. We further showed that the excellent performance of the newly proposed BM/BiFeOxHy electrocatalysts is attributed to the utilization of Fe/Bi-O hybridization, the induced amorphous structure, and increased lattice vacancies, which are systematically demonstrated by the electrochemical and physicochemical analysis and theoretical density functional theory (DFT) calculation. Bi metal/BiFe (oxy)hydroxides (BM/BiFeOxHy) heterostructure with internal voids was obtained by simple solvothermal process under reduction environment. Oxygen evolution reaction (OER) of BM/BiFeOxHy evolved Bi metal into high valence state, which enables lattice oxygen mechanism (LOM). [Display omitted] •BM/BiFeOxHy with lattice vacancies was developed by a simple solvothermal synthesis.•Electrode shows the long-term OER operation at high current density of 1000 mA cm-2.•Fe/Bi-O hybridization and the induced amorphous structure increase the performance.•DFT has confirmed lattice oxygen mechanism (LOM) in the OER activity of BM/BiFeOxHy.