Photocatalytic CO ₂ –to–Ethylene Conversion over Bi ₂ S ₃ /CdS Heterostructures Constructed via Facile Cation Exchange

Abstract

Solar-driven CO 2 conversion to multicarbon (C 2+ ) products has emerged as a key challenge, yet this calls for a systematic investigation on the overall reaction process and mechanism at an atomic level based on the rational design of highly selective photocatalysts. Herein, we report the synthesis of compact Bi 2 S 3 /CdS heterostructures via facile cation exchange, by which a unique pathway of CO 2 –to–C 2 H 4 photoconversion is achieved. Specifically, the BCS–30 shows an optimal C 2 H 4 production rate of 3.49 μ mol h −1 g −1 based on the regulation of band structures and energy levels of photocatalysts by controlled growth of Bi 2 S 3 at CdS surface. Both experimental and theoretical results (DFT calculations) identify Bi atoms as new catalytic sites for the adsorption of CO <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow/> <mml:mrow> <mml:mo>∗</mml:mo> </mml:mrow> </mml:msup> </mml:math> and formation of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow/> <mml:mrow> <mml:mo>∗</mml:mo> </mml:mrow> </mml:msup> </mml:math> CO− <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow/> <mml:mrow> <mml:mo>∗</mml:mo> </mml:mrow> </mml:msup> </mml:math> CO dimers that further hydrogenate to produce ethylene. Overall, this work demonstrates vast potentials of delicately designed heterostructures for CO 2 conversion towards C 2+ products under mild photocatalytic conditions.