AlP-regulated phosphorus vacancies over Ni-P compounds promoting efficient and durable hydrogen generation in acidic media

• Published in: Dalton transactions : an international journal of inorganic chemistry 2022-03, Vol.51 (1), p.433-442
• Main Authors: Wang, Mei, Zhao, Huifang, Long, Yi, Zhang, Wenjuan, Wang, Liyong, Zhou, Diaoyu, Wang, Huiqi, Wang, Xiaoguang
• Format: Article
• Language: English
• Subjects: Aluminum; Catalysts; Density functional theory; Electrocatalysts; Electron paramagnetic resonance; Electron states; Electronic structure; Gibbs free energy; High resolution electron microscopy; Hydrogen evolution reactions; Hydrogen production; Nickel compounds; Phosphating (coating); Phosphides; Phosphorus; Structural hierarchy; Vacancies
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d1dt04346c

Engineered anion vacancy catalysts exhibit speedy activity in the field of electrocatalysis due to their tunable electronic structure and moderate free energy of adsorbed intermediates. Herein, we demonstrate a facile process of preparing multiphase phosphides with abundant phosphorus vacancies (P V ) supported on nanoporous Ni(Al). X-ray diffraction (XRD), electron paramagnetic resonance (EPR) and high-resolution transmission electron microscopy (HRTEM) reveal that the as-obtained material has ample P V induced by the AlP phase. The optimized catalyst also equips with aligned nanoflakes grown in situ on np-Ni(Al) skeletons/ligaments, thereby exposing a large specific surface area for hydrogen evolution reactions (HERs) in acidic media. Benefitting from its unique hierarchical structure and sufficient P V , the P V -np-Ni(Al)-40 electrode displays a low overpotential of 36 mV at a cathodic current density of 10 mA cm −2 and an outstanding long-term operational stability for up to 94 h with a slight decay. Density functional theory (DFT) calculations confirm that P V could induce the redistribution of electrons and significantly reduce the Gibbs free energy (Δ G H* ) of 2P V -NiP 2 on the P site close to P V (−0.055 eV). Moreover, the P V is beneficial for enriching the electronic states nearby the Fermi level, thereby improving the conductivity of NiP 2 to achieve superior HER activity. This finding skillfully utilizes Al elements to not only create porous structures but also regulate the P V concentration, opening up an accessible route to obtain P V via dealloying-phosphorization, and boosting the development of high-performance HER electrocatalyst. Through experimental and theoretical investigations, multiphase phosphide nanoflakes equipped with AlP-induced phosphorus vacancies (P V ) are proved to be efficient electrocatalysts for boosting hydrogen production.