Unconventional hcp/fcc Nickel Heteronanocrystal with Asymmetric Convex Sites Boosts Hydrogen Oxidation

• Published in: Angewandte Chemie International Edition 2024-09, Vol.63 (39), p.e202409763-n/a
• Main Authors: Pan, Hai‐Rui, Shi, Zhuo‐Qi, Liu, Xiao‐Zhi, Jin, Shifeng, Fu, Jiaju, Ding, Liang, Wang, Shu‐Qi, Li, Jian, Zhang, Linjuan, Su, Dong, Ling, Chongyi, Huang, Yucheng, Xu, Cailing, Tang, Tang, Hu, Jin‐Song
• Format: Article
• Language: English
• Subjects: Adsorption; adsorption configuration; Asymmetry; Catalysts; coherent stacking faults; Control stability; Fuel cells; heterointerface; Hydrogen; Hydrogen oxidation reaction; Intermediates; Nickel; Oxidation; Platinum metals; Surface chemistry; Surface stability; Twin boundaries
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202409763

Developing non‐platinum group metal catalysts for the sluggish hydrogen oxidation reaction (HOR) is critical for alkaline fuel cells. To date, Ni‐based materials are the most promising candidates but still suffer from insufficient performance. Herein, we report an unconventional hcp/fcc Ni (u‐hcp/fcc Ni) heteronanocrystal with multiple epitaxial hcp/fcc heterointerfaces and coherent twin boundaries, generating rugged surfaces with plenty of asymmetric convex sites. Systematic analyses discover that such convex sites enable the adsorption of *H in unusual bridge positions with weakened binding energy, circumventing the over‐strong *H adsorption on traditional hollow positions, and simultaneously stabilizing interfacial *H2O. It thus synergistically optimizes the HOR thermodynamic process as well as reduces the kinetic barrier of the rate‐determining Volmer step. Consequently, the developed u‐hcp/fcc Ni exhibits the top‐rank alkaline HOR activity with a mass activity of 40.6 mA mgNi−1 (6.3 times higher than fcc Ni control) together with superior stability and high CO‐tolerance. These results provide a paradigm for designing high‐performance catalysts by shifting the adsorption state of intermediates through configuring surface sites. A molecular precursor‐directed strategy is developed to construct unconventional Ni heteronanocrystals with multiple epitaxial hcp/fcc heterointerfaces and coherent twin boundaries, generating asymmetric surfaces with plenty of convex sites. Such unique convex sites enable the adsorption of *H in unusual bridge positions with weakened binding energy while stabilizing interfacial *H2O, synergistically facilitating alkaline hydrogen oxidation reaction.