Search

As the main component of syngas, reducing CO2 to CO with high selectivity through photocatalysis could provide a sustainable way to alleviate energy shortage issues. Developing a photocatalytic system with low cost and high performance that is environmentally friendly is the ultimate goal towards CO2 photoreduction. Herein, an efficient and economic three‐component heterojunction photocatalyst is designed and fabricated for converting CO2 to CO in the absence of organic sacrificial agents. The heterojunction is made of Cu2−xS nanotubes coated with a carbon layer (C‐Cu2−xS) and g‐C3N4. By using the classical MOF material HKUST‐1 as a precursor, hollow tubular‐like metal sulfides (C‐Cu2−xS) with carbon coating were synthesized and further loaded on g‐C3N4, forming a three‐component heterojunction C‐Cu2−xS@g‐C3N4. The carbon coat in C‐Cu2−xS@g‐C3N4 acts as an electron reservoir, which facilitates electron–hole pair separation. The optimized C‐Cu2−xS@g‐C3N4 acted as a photocatalyst in CO2 reduction with a high reactivity of 1062.6 μmol g−1 and selectivity of 97 %. Compared with bare g‐C3N4 (158.4 μmol g−1) and C‐Cu2−xS, the reactivity is nearly 7 and 23‐fold enhanced and this CO generation rate is higher than most of the reported Cu2S or g‐C3N4 composites under similar conditions. The prominent activity may result from enhanced light adsorption and effective charge separation. This work might open up an alternative method for the design and fabrication of high‐performance and low‐cost photocatalysts for efficiently and durably converting CO2 to CO with high selectivity. CO2 photoreduction: An efficient and economic three‐component heterojunction photocatalyst is designed and fabricated for converting CO2 to CO in the absence of organic sacrificial agents. The heterojunction is made of Cu2−xS nanotubes coated with a carbon layer (C‐Cu2−xS) and loaded onto g‐C3N4. [ABSTRACT FROM AUTHOR]

A hydrazone-based covalent organic framework/iridium (III) complex heterogeneous system for photochemical CO 2 reduction with high efficiency, excellent selectivity and durability. • A hydrazone COF/Ir complex for CO 2 reduction with high reactivity and selectivity. • The catalytic durability improved by an order of magnitude. • The electrons excitation paths in the heterogeneous system follow Z-scheme. Metal complexes have been one of the most promising photocatalysts for highly selective conversion of CO 2 to carbon-based products. However, the aggregation-induced deactivation and narrow absorption range of sunlight impede their catalytic performance. Here, a heterogeneous photocatalytic system with a hydrazone-based covalent organic framework (COF) as photosensitizer and a metal complex [Ir-ppy] as photocatalyst is designed for efficient and durable photochemical CO 2 reduction. Under visible-light irradiation, this heterogeneous system achieves CO yield of 88.6 μmol in 1 h's reaction with the selectivity of 98%. This reactivity is 2.3 times higher than that of bare [Ir-ppy]. Significantly, comparing with the poor catalytic durability (30 min) of [Ir-ppy], the COF/[Ir-ppy] catalyst still be active after irradiation of 7 h. The extended catalytic reactivity may result from the promoting dispersion of [Ir-ppy] on NAHN-Tp COF which restrains the aggregation-induced deactivation of [Ir-ppy]. The enhanced reactivity may originate from the efficient electron transfer from COF to [Ir-ppy] and facilitated photo-induced charge separation as evidenced by matched band alignment of COF and [Ir-ppy], steady-state photoluminescence, time-resolved fluorescence. [ABSTRACT FROM AUTHOR]