Photothermal catalyzed hydrogenation of carbon dioxide over porous nanosheet Co3O4

A series of Co 3 O 4 catalysts were prepared by hydrothermal method in the solvent with different ethanol/water ratios for photothermal CO 2 reduction. Results of performances showed that the prepared Co 3 O 4 catalysts with porous nanosheet structures exhibited excellent catalytic activity. The Co 3 O 4 prepared with the ethanol/water ratio of 1/1, denoted as Co 3 O 4 (1/1), presented more than 50% CO 2 conversion and 95% CH 4 selectivity, which were higher than other Co 3 O 4 prepared with ethanol/water ratios of 1/0, 1/2, and 1/4. Results of characterizations showed that Co 3 O 4 (1/1) exhibited the highest concentration of surface -OH sites among these above five catalysts. The surface -OH sites played a critical role in the formation of bidentate species during CO 2 hydrogenation, which is one of most important intermediates for the CH 4 generation. • On the condition of successive reaction, Co 3 O 4 has good photothermal catalytic performance. • Bidentate intermediates benefits CO 2 hydrogenation to methane. • The effect of the ratio of water to ethanol on the catalytic activity in the hydrothermal method was studied.