Solar-driven catalytic oxidation of 5-hydroxymethylfurfural (HMF) into 2,5-diformylfuran (DFF) coupled with H2 evolution has been considered a promising approach. The exploration of an active and stable photocatalyst still remains challenging work. Herein, we found that the flexible ultrathin graphitic carbon nitride (UCNT) could be an ideal candidate. The UCNT exhibits photocatalytic performance in selective oxidation of HMF into DFF coupled with H2 evolution with activities of 95.0 and 92.0 μmol g–1 h–1 under visible light irradiation. Importantly, the UCNT also demonstrates high DFF selectivity (95%) and good cycling stability. The activity may be ascribed to the strong specific interaction between HMF and UCNT. Solid-state nuclear magnetic resonance (NMR) and density functional theory (DFT) results reveal that the twisted structure of HMF molecules could form a strong interaction between HMF and UCNT, reducing the dehydrogenation energy barrier for HMF oxidation. In addition, mechanistic studies reveal that •C6H4O3 is the key radical intermediate during the HMF oxidation process by a in situ electron spin resonance (ESR) trapping test. Our work clarifies the interaction of complex biomass molecules on the flexible catalyst surface and provides views on the further development of heterogeneous catalytic biomass conversion.

Simultaneous photocatalytic H2 production and preparation of high-value chemicals by the selective oxidation of organic substances is of great significance for solar energy utilization and conversion. Herein, a Pt-modified 2D/2D CdS/Fe2O3 Z-scheme heterojunction was dexterously designed for photocatalytic dehydrogenation coupling of benzylamine with high performance and product selectivity. The Z-scheme charge transfer in CdS/Fe2O3 greatly boosts charge separation and maintains the strong redox capacity of photogenerated electrons and holes. Impressively, the loading of the Pt cocatalyst not only provides rich H2 production active sites to further accelerate charge separation and H2 production kinetics but also facilitates the condensation of N-benzylideneamine with benzylamine for N-benzylidenebenzylamine production and NH3 releasing. The selectivity for CN coupling products is significantly enhanced and the C–C coupling side reaction is greatly suppressed. With sufficient benzylamine substrate and visible light irradiation, the optimal Pt/CdS/Fe2O3 composite displays a high H2 production rate of 39.4 mmol h–1 g–1 with a quantum efficiency of 32.81% at 420 nm, and the selectivity of benzylamine oxidation to N-benzylidenebenzylamine is above 90%.

Overall water splitting to generate H 2 and O 2 is vital in solving energy problem. It is still a great challenge to seek efficient visible light photocatalyst to realize overall water splitting. In this work, the tetragonal zircon BiVO 4 is prepared by epitaxial growth on FTO substrate and its overall water splitting reaction is studied. Under the influence of epitaxial strain, the conduction band position shifts negatively and beyond H + /H 2 reduction potential (0 V vs NHE), which enables it to possess the photocatalytic hydrogen evolution activity. After loading cocatalysts, the overall water splitting (𝝀 > 400 nm) is realized (H 2 : ≈65.7 μmol g −1 h −1 , O 2 : ≈32.6 μmol g −1 h −1 ), and the value of solar hydrogen conversion efficiency is 0.012%. The single-particle photoluminescence (PL) spectra and PL decay kinetics tests demonstrate the cocatalysts are beneficial to the separation and transfer of carriers. The new strategy of adjusting the band structure by strain is provided.

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