Simultaneous Manipulation of Bulk Excitons and Surface Defects for Ultrastable and Highly Selective CO₂ Photoreduction

Abstract

The objective of photocatalytic CO2 reduction (PCR) is to achieve high selectivity for a single energy‐bearing product with high efficiency and stability. The bulk configuration usually determines charge carrier kinetics, whereas surface atomic arrangement defines the PCR thermodynamic pathway. Concurrent engineering of bulk and surface structures is therefore crucial for achieving the goal of PCR. Herein, an ultrastable and highly selective PCR using homogeneously doped BiOCl nanosheets synthesized via an inventive molten strategy is presented. With B2O3 as both the molten salt and doping precursor, this new doping approach ensures boron (B) doping from the surface into the bulk with dual functionalities. Bulk B doping mitigates strong excitonic effects confined in 2D BiOCl by significantly reducing exciton binding energies, whereas surface‐doped B atoms reconstruct the BiOCl surface by extracting lattice hydroxyl groups, resulting in intimate B‐oxygen vacancy (B‐OV) associates. These exclusive B‐OV associates enable spontaneous CO2 activation, suppress competitive hydrogen evolution and promote the proton‐coupled electron transfer step by stabilizing *COOH for selective CO generation. As a result, the homogeneous B‐doped BiOCl nanosheets exhibit 98% selectivity for CO2‐to‐CO reduction under visible light, with an impressive rate of 83.64 µmol g−1 h−1 and ultrastability for long‐term testing of 120 h.

Novel Cerium‐Based Sulfide Nano‐Photocatalyst for Highly Efficient CO2Reduction

“…The results of in situ FTIR spectra above have shown that the photoreduction of CO 2 to CO occurs through the COOH* and CO* on Ce ions of NaCeS 2 NCs, where the formation of COOH* is regarded to be the determining‐limiting step. [ 9,38,39 ] According to the calculated results shown in Figure a, the formation of COOH* intermediates over the NaCeS 2 NCs was endothermic and involved a large activation energy barrier (0.92 eV) (Tables S1 and S2, Supporting Information), thereby confirming that the CO 2 ‐to‐COOH* activation was the determining‐limiting step in the CO 2 photoreduction process. Next, the Gibbs free energy of CO* and CO were 0.36 and 0.56 eV, respectively, which means that absorbing 0.20 eV (∆E = ∆G CO − ∆G CO* ) was indispensable from the environment in CO desorption reaction (CO* → CO).…”

Emerging Strategies for CO2 Photoreduction to CH4: From Experimental to Data‐Driven Design

“…[74,76,77] Impurity doping is one of the most commonly used strategies for enhancing photocatalysis performance, with the ability to extend the absorption range of the light spectrum, [78] modify band position, [79] enhance the stability of positive electric charge, and promote charge carrier excitation and separation. [80] Both nonmetals [81][82][83][84][85] and metals [86][87][88] can be used as dopant elements with slightly different mechanisms and effects. For example, metal doping can trap electrons and promote photoinduced electron-hole separation, [89] leading to enhanced redox ability.…”

Engineering Nonprecious Metal Oxides Electrocatalysts for Two‐Electron Water Oxidation to H2O2

“…This operando Raman spectroscopy results undoubtedly reveal that the O v in BiVO 4 can significantly promote water dissociation, and thus suppress the production of H 2 O 2 , consistent with the experimental results. Different from the prevalence of operando characterizations in other electrocatalytic fields like water splitting, [64][65][66][67] carbon dioxide reduction, [68][69][70] and nitrogen fixation, [71,72] the 2e-WOR related operando measurements is still in its infancy and much more efforts are desirable.…”