Surface frustrated Lewis pairs in titanium nitride enable gas phase heterogeneous CO<sub>2</sub> photocatalysis.

Zou, Yunjie; Mao, Chengliang; Xu, Mingkai; Xing, Chao; Wang, Ruizhao; Ozin, Geoffrey A; Ling, Lan · Nat Commun · 2024

basic_science · Level V

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Abstract

Gas-phase heterogeneous catalytic CO<sub>2</sub> hydrogenation to commodity chemicals and fuels via surface frustrated Lewis pairs is a growing focus of scientific and technological interest. Traditional gas-phase heterogeneous surface frustrated Lewis pair catalysts primarily involve metal oxide-hydroxides (MOH•••M). An avenue to improve the process performance metrics lies in replacing the Lewis base MOH with a stronger alternative; an intriguing example being the amine MNH<sub>2</sub> in metal nitrides. This study establishes a proof-of-concept that an amine-type photoactive surface frustrated Lewis pair (MNH<sub>2</sub>•••M) can be constructed in titanium nitride (TiN<sub>x</sub>O<sub>y</sub>) when integrated with a nanoscale platinum spillover co-catalyst. This surface frustrated Lewis pair, comprising Ti-NH<sub>2</sub> as the Lewis base and low-valent Ti as the Lewis acid, facilitates the gas-phase light-assisted heterogeneous reverse water-gas shift reaction. The reaction proceeds via a surface-active carbamate intermediate, Ti-(H<sub>2</sub>N-COO)-Ti, whereby the synergism of Lewis acidic and Lewis basic sites endows it with superior performance indicators compared to TiN<sub>x</sub>O<sub>y</sub> alone, as well as conventional platinum supported metal oxides.