Boosted Sacrificial-Agent-Free Selective Photoreduction of CO 2 to CH 3 OH by Rhenium Atomically Dispersed on Indium Oxide.

Solar-energy-driven photoreduction of CO 2 is promising in alleviating environment burden, but suffers from low efficiency and over-reliance on sacrificial agents. Herein, rhenium (Re) is atomically dispersed in In 2 O 3 to fabricate a 2Re-In 2 O 3 photocatalyst. In sacrificial-agent-free photoreduction of CO 2 with H 2 O, 2Re-In 2 O 3 shows a long-term stable efficiency which is enhanced by 3.5 times than that of pure In 2 O 3 and is also higher than those on Au-In 2 O 3 , Ag-In 2 O 3 , Cu-In 2 O 3 , Ir-In 2 O 3 , Ru-In 2 O 3 , Rh-In 2 O 3 and Pt-In 2 O 3 photocatalysts. Moreover, carbon-based product of the photoreduction overturns from CO on pure In 2 O 3 to CH 3 OH on 2Re-In 2 O 3 . Re promotes charge separation, H 2 O dissociation and CO 2 activation, thus enhancing photoreduction efficiency of CO 2 on 2Re-In 2 O 3 . During the photoreduction, CO is a key intermediate. CO prefers to desorption rather than hydrogenation on pure In 2 O 3 , as CO binds to pure In 2 O 3 very weakly. Re strengthens the interaction of CO with 2Re-In 2 O 3 by 5.0 times, thus limiting CO desorption but enhancing CO hydrogenation to CH 3 OH. This could be the origin for photoreduction product overturn from CO on pure In 2 O 3 to CH 3 OH on 2Re-In 2 O 3 . The present work opens a new way to boost sacrificial-agent-free photoreduction of CO 2 .