B, N Codoped Defective Reduced Graphene Oxide as a Highly Efficient Frustrated Lewis Pairs Catalyst for the Selective Hydrogenation of α,β-Unsaturated Aldehydes to Unsaturated Alcohols

The development of all-solid-state frustrated Lewis pairs (FLPs) metal-free hydrogenation catalysts with excellent activity and stability remains a significant challenge. In this work, B, N codoped FLPs catalysts (De-rGO-N_xB_y) were prepared by the strategy of fabricating carbon defects and heteroatom doping on the surface of reduced graphene oxide and applied in the selective hydrogenation of α,β-unsaturated aldehydes to unsaturated alcohols. It was found that electron-rich pyridine-N (Lewis base) and adjacent electron-deficient B–N (Lewis acid) sites could be constructed on the surface of reduced graphene oxide using dicyandiamide and metaboric acid as N and B sources, thus forming FLPs sites. More importantly, the constructed carbon defects could facilitate the formation of pyridinic-N/B–N FLPs sites, thereby improving the catalytic hydrogenation activity and the selectivity to unsaturated alcohols. Furthermore, in situ DRIFTS and DFT calculations show that the pyridinic-N/B–N FLPs sites can efficiently activate the C═O of aldehydes and H₂ molecules with only 0.53 eV dissociation energy of the H–H bond. Also, the catalyst presents excellent catalytic performance in the transfer hydrogenation reactions with cyclohexanol and its derivatives as hydrogen sources. This study provides new ideas for the design and preparation of all-solid-state FLPs metal-free catalysts and promotes the green synthesis of unsaturated alcohols.