Engineering heteroatomic structures in Pt single-atom anchored covalent organic frameworks for enhanced photocatalytic hydrogen evolution reaction

Abstract

We report a groundbreaking heteroatomic structural engineering approach to significantly enhance the photocatalytic hydrogen evolution reaction (HER) performance of covalent organic frameworks (COFs). By strategically incorporating triazine, secondary amine, and β-ketoenamine linkages into the COF architecture, we achieved precise control over the distribution of platinum (Pt) cocatalysts, transitioning from nanoparticles to single atoms. The optimized COF, TAPAT–TFP, which integrates all three heteroatomic groups, exhibited an exceptional photocatalytic HER rate of 2.39 mmol g⁻¹ h⁻¹ under visible light (≥420 nm), outperforming TAPA–TFP (0.41 mmol g⁻¹ h⁻¹) by nearly 5.8 times and surpassing TAPA–TFB, which showed negligible activity. Central to this advancement is the anchoring of Pt single atoms at β-ketoenamine and –NH– sites, as confirmed by a combination of experimental analyses and density functional theory (DFT) calculations. The Pt single atoms not only enhance charge separation and transfer efficiency but also provide a high density of active sites for redox reactions, resulting in a remarkable turnover frequency (TOF) of 150.4 h⁻¹ at a low Pt loading of 0.31 wt%. Our findings underscore the pivotal role of heteroatomic structural engineering in modulating the photoelectrochemical properties of COFs, including band gap adjustments and enhanced Pt precursor adsorption. The successful integration of single-atom Pt cocatalysts into COFs, validated by X-ray absorption spectroscopy (XAS) and DFT calculations, offers new insights into the design of high-performance photocatalysts for sustainable hydrogen production. This work not only highlights the potential of COFs as efficient photocatalysts but also provides a robust framework for the rational design of single-atom catalysts, paving the way for future advancements in solar-driven hydrogen generation. The innovative approach presented here opens new avenues for the development of next-generation photocatalysts with enhanced efficiency and stability.