Unveiling the Synergistic Role of Frustrated Lewis Pairs in Carbon‐Encapsulated Ni/NiOx Photothermal Cocatalyst for Enhanced Photocatalytic Hydrogen Production

• Published in: Advanced materials (Weinheim) 2024-06, Vol.36 (24), p.e2313513-n/a
• Main Authors: Yang, Zhi, Huang, Taiyu, Li, Meng, Wang, Xudong, Zhou, Xiaosong, Yang, Siyuan, Gao, Qiongzhi, Cai, Xin, Liu, Yingju, Fang, Yueping, Wang, Yu, Zhang, Shanqing, Zhang, Shengsen
• Format: Article
• Language: English
• Subjects: Adsorbed water; Carbon; Carbon nitride; Crystal defects; Density; Encapsulation; frustrated Lewis pairs; Grain boundaries; Hydrogen production; Jahn-Teller effect; Ni/NiOx@C; Photocatalysis; photothermal
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.202313513

The development of high‐density and closely spaced frustrated Lewis pairs (FLPs) is crucial for enhancing catalyst activity and accelerating reaction rates. However, constructing efficient FLPs by breaking classical Lewis bonds poses a significant challenge. Here, this work has made a pivotal discovery regarding the Jahn–Teller effect during the formation of grain boundaries in carbon‐encapsulated Ni/NiOx (Ni/NiOx@C). This effect facilitates the formation of high‐density O (VO) and Ni (VNi) vacancy sites with different charge polarities, specifically FLP‐VO‐C basic sites and FLP‐VNi‐C acidic sites. The synergistic interaction between FLP‐VO‐C and FLP‐VNi‐C sites not only reduces energy barriers for water adsorption and splitting, but also induces a strong photothermal effect. This mutually reinforcing effect contributes to the exceptional performance of Ni/NiOx@C as a cocatalyst in photothermal‐assisted photocatalytic hydrogen production. Notably, the Ni/NiOx@C/g‐C3N4 (NOCC) composite photocatalyst exhibits remarkable hydrogen production activity with a rate of 10.7 mmol g−1 h−1, surpassing that of the Pt cocatalyst by 1.76 times. Moreover, the NOCC achieves an impressive apparent quantum yield of 40.78% at a wavelength of 380 nm. This work paves the way for designing novel defect‐state multiphase cocatalysts with high‐density and adjacent FLP sites, which hold promise for enhancing various catalytic reactions. High‐density oxygen (VO) and nickel (VNi) vacancies are formed at the interface of Ni/NiOx encapsulated in graphitized carbon (Ni/NiOx@C) due to the Jahn–Teller effect during polycrystalline annealing. These vacancies establish highly active frustrated Lewis pairs, which significantly enhance the processes of water adsorption and dissociation. Moreover, the defect‐induced nonradiative recombination in Ni/NiOx@C facilitates efficient photothermal‐assisted photocatalytic hydrogen production.