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

Abstract

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/NiO_x@C). This effect facilitates the formation of high-density O (V_O) and Ni (V_Ni) vacancy sites with different charge polarities, specifically FLP-V_O-C basic sites and FLP-V_Ni-C acidic sites. The synergistic interaction between FLP-V_O-C and FLP-V_Ni-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/NiO_x@C as a cocatalyst in photothermal-assisted photocatalytic hydrogen production. Notably, the Ni/NiO_x@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.