Revealing the Sudden Alternation in Pt@h‐BN Nanoreactors for Nearly 100% CO2‐to‐CH4Photoreduction

Abstract How to develop an efficient photocatalyst with high activity and high selectivity is the biggest challenge limiting the application of photocatalysis. A reasonable design of the nanoreactor model is an effective strategy. Herein, a series of Pt nanoparticles coated with hexagonal boron nitride (Pt@h‐BN) nanoreactors highly dispersed on a photochemically inert carrier, Al 2 O 3 substrate, are synthesized. The results show that as the number of h‐BN coating layers increases, the selectivity of photocatalysis is altered from nearly 100% CO 2 ‐to‐CO to nearly 100% CO 2 ‐to‐CH 4 , and the optimized space‐time yield of CH 4 is up to 184.7 μmol g (Pt) −1 h −1 with three‐layer coating. The in situ characterizations reveal the cleavage of the CO on Pt to be the rate determining step and the existence of the key intermediate CO 2 − species on the surface of Pt@h‐BN facilitates CH 4 formation. Notably, combined with detailed simulation calculations, this work reveals that the confinement effect in Pt@h‐BN attributes the electrons mobility behavior and alleviate the interaction of COPt. What is more, the change of the reaction site is the essence for the sudden alternation. This work will bring a new insight to the selective catalysis of noble metals in the gas‐solid phase.