Renewable biomass-derived, P-doped granular activated carbon for efficient oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran: Insights into the crucial role of P and N functionality

Heteroatom-doped carbon materials for eco-friendly metal-free catalysis have gained increasing attention, but they nevertheless face technological challenges relating to the difficult recycling and high cost. In this work, P-doped granular activated carbons with intrinsic N functionality (PN-GAC-T) were successfully fabricated from low-cost and sustainable waste peanut shells using a simple self-bonding strategy assisted by phosphoric acid. The as-prepared PN-GAC-T were found to have abundant N, P functional groups and large specific surface areas, making them potentially efficient metal-free catalysts for the selective oxidation of 5-hydroxymethylfurfural (HMF). Catalytic results showed that an excellent HMF conversion (98.4%) and 2,5-diformylfuran (DFF) selectivity (99.7%) could be achieved under mild conditions via employing PN-GAC-800 as a catalyst. The good catalytic performance of PN-GAC-800 is highly reliant on the synergistic effect between doped P and intrinsic N functionalities as verified by the control experiments. Furthermore, the density functional theory (DFT) calculations demonstrated that the introduction of both P and N functional groups would aid in the activation of HMF and the improvement of oxygen adsorption capability. This work has emphasized the possibility of high-value exploitation of biomass waste, and it is predicted to provide new inspiration for the development of readily recyclable heteroatom-doped carbon catalysts.