Unveiling the surface hydroxylation and selenite modification of generated nickel for promoting the hydrogen evolution reaction

• Published in: Inorganic chemistry frontiers Vol. 11; no. 11; pp. 3357 - 3366
• Main Authors: Guo, Kailu, Jia, Jinzhi, Wang, Huijiao, Xu, Cailing
• Format: Journal Article
• Published: 28.05.2024
• ISSN: 2052-1553
• DOI: 10.1039/d4qi00532e

Understanding the structural reconstruction of Ni-based materials under electro-reduction conditions and identifying the real active species in the alkaline hydrogen evolution reaction (HER) are significant for developing low-cost and efficient electrocatalysts. Moreover, the role of surface-adsorbed ions has not been fully elucidated after electrochemical reconstruction and severe leaching. Herein, taking (Ni 12 (OH) 6 (SeO 3 ) 8 )(OH) 2 crystal as a pre-catalyst, multiple in situ and ex situ techniques verify that (Ni 12 (OH) 6 (SeO 3 ) 8 )(OH) 2 is destroyed rapidly in the alkaline HER process and reconstructs into metallic Ni, followed by spontaneous surface hydroxylation, ultimately transforming into a Ni/Ni(OH) 2 heterostructure decorated with a small amount of selenite (SeO 3 2− ). The resulting material exhibits a low overpotential of 35 mV for HER at −10 mA cm −2 in 1 M KOH and can be operated at −300 mA cm −2 for 120 h without noticeable attenuation, outperforming most non-noble metal electrocatalysts. Theoretical calculations further prove that the surface-adsorbed SeO 3 2− can regulate the electronic states of Ni sites, reduce the energy barrier of H 2 O-dissociation, and optimize the hydrogen adsorption free energy. These findings provide insight into the structural transformation mechanism and active species of electrode materials during the alkaline HER process. An electrochemical activation process for Ni-Se-O-H crystal has been found to produce a Ni/Ni(OH) 2 heterostructure decorated with a small amount of SeO 3 2− , exhibiting superior alkaline HER activity and durability.