Efficient transformation of CO2 into α-alkylidene cyclic carbonates over Cu0/Cu+ derived from CuAl layered double hydroxide/reduced graphene oxide hybrid

Abstract

A simple liquid-phase co-precipitation method was used to achieve a good dispersion of CuAl layered double hydroxide (CuAl-LDH) on the surface of graphene oxide (GO), and Cu2+ in the lattice of CuAl-LDH was in-situ reduced to Cu0 and Cu+ species, resulting in the preparation of R-CuAl-LDH/rGO catalyst. It could effectively catalyze the cyclization of CO2 and propargylic alcohols under mild conditions (50 °C and 1 bar), and the yield exceeded 99 % within only 40 min. Systematic characterization revealed that two-dimensional LDH nanosheets were grown on the rGO surface in an irregular orientation, leading to a higher specific surface area and more abundant surface active sites. Meanwhile, the synergistic catalysis of Cu0 and Cu+ dual-active sites greatly enhanced the catalytic efficiency. In addition, the catalyst had excellent recycling properties with no significant loss of activity after 5 cycles of continuous operation.