Construction of internal electric fields (IEFs) is crucial to realize efficient charge separation for charge-induced redox reactions, such as water splitting and CO2 reduction. However, a quantitative understanding of the charge transfer dynamics modulated by IEFs remains elusive. Here, electron microscopy study unveils that the non-equilibrium photo-excited electrons are collectively steered by two contiguous IEFs within binary (001)/(200) facet junctions of BiOBr platelets, and they exhibit characteristic Gaussian distribution profiles on reduction facets by using metal co-catalysts as probes. An analytical model justifies the Gaussian curve and allows us to measure the diffusion length and drift distance of electrons. The charge separation efficiency, as well as photocatalytic performances, are maximized when the platelet size is about twice the drift distance, either by tailoring particle dimensions or tuning IEF-dependent drift distances. The work offers great flexibility for precisely constructing high-performance particulate photocatalysts by understanding charge transfer dynamics. 

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Unveiling the charge transfer dynamics steered by built-in electric fields in BiOBr photocatalysts

The solar‐energy‐driven photoreduction of CO2 has recently emerged as a promising approach to directly transform CO2 into valuable energy sources under mild conditions. As a clean‐burning fuel and drop‐in replacement for natural gas, CH4 is an ideal product of CO2 photoreduction, but the development of highly active and selective semiconductor‐based photocatalysts for this important transformation remains challenging. Hence, significant efforts have been made in the search for active, selective, stable, and sustainable photocatalysts. In this review, recent applications of cutting‐edge experimental and computational materials design strategies toward the discovery of novel catalysts for CO2 photocatalytic conversion to CH4 are systematically summarized. First, insights into effective experimental catalyst engineering strategies, including heterojunctions, defect engineering, cocatalysts, surface modification, facet engineering, and single atoms, are presented. Then, data‐driven photocatalyst design spanning density functional theory (DFT) simulations, high‐throughput computational screening, and machine learning (ML) is presented through a step‐by‐step introduction. The combination of DFT, ML, and experiments is emphasized as a powerful solution for accelerating the discovery of novel catalysts for photocatalytic reduction of CO2. Last, challenges and perspectives concerning the interplay between experiments and data‐driven rational design strategies for the industrialization of large‐scale CO2 photoreduction technologies are described.

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

Bimetallic silver/bismuth-MOFs derived strategy for Ag/AgCl/BiOCl composite with extraordinary visible light-driven photocatalytic activity towards tetracycline

Synthesis, Functional Modifications, and Diversified Applications of Hybrid BiOCl-Based Heterogeneous Photocatalysts: A Review

Fast preparation of oxygen vacancy-rich 2D/2D bismuth oxyhalides-reduced graphene oxide composite with improved visible-light photocatalytic properties by solvent-free grinding

Facet Junction Engineering for Photocatalysis: A Comprehensive Review on Elementary Knowledge, Facet-Synergistic Mechanisms, Functional Modifications, and Future Perspectives

One-pot construction of Ta-doped BiOCl/Bi heterostructures toward simultaneously promoting visible light harvesting and charge separation for highly enhanced photocatalytic activity

Uncovering the contribution of anisotropic crystal facets in single‐crystalline photocatalysts is still a challenge in fundamental study. Here, the mechanism underlying facet junction‐dependent photocharge separation in polyhedral Cu2O is demonstrated, which is beneficial for understanding why 50‐faceted Cu2O exhibiting quaternary {100}/{110}/{111}/{522} facet junction possesses an enhanced photodegradation activity toward tetracycline than that of the 26‐faceted Cu2O exhibiting ternary {100}/{110}/{111} and 18‐faceted Cu2O exhibiting binary {100}/{110} facet junction. Density functional theory (DFT) calculations and selective photodeposition results confirm that hierarchical facet junctions are formed in a 50‐faceted Cu2O, which could be regarded as one parallel connection between binary {110}/{111} and ternary {110}/{522}/{100} series facet junction for conduction band minimum, and another parallel connection between binary {100}/{522} and ternary {111}/{110}/{522} series facet junction for valence band maximum, leading to an unprecedented dual series‐parallel transfer pathway for more efficiently improved photocharge separation. Hopefully, this study would be a beneficial guideline for scientific researchers currently concentrating on the facet junction engineering of polyhedral photocatalysts.

Mechanism Insight into an Unprecedented Dual Series‐Parallel Photocharge Separation in Quaternary Cu2O Facet Junctions

Tungsten-based catalyst has been widely investigated in the field of selective hydrogenolysis of secondary CO bond, such an important yet challenging strategy, in glycerol conversion, in which the product 1,3-propanediol (1,3-PDO) is of great value in polyester industry. Unfortunately, though it has been proved to be highly active, the identification of the intrinsic tungsten oxide active sites still remains unrevealed to date due to its complex microstructure. Herein, we incorporate atomically dispersed alumina as promoter in the context of the selective hydrogenation of glycerol and report a Pt/Al-WOx catalyst. This catalyst decidedly outperforms the unpromoted Pt/WOx, which elevates the 1,3-PDO yield to 2 times. Spectroscopy characterizations and chemisorption experiments have revealed that the high activity and selectivity of Pt/Al-WOx catalyst results from the more oxygen vacancies on WOx in-situ generation by the acceleration of atomically dispersed alumina in hydrogen atmosphere, which increases the selective adsorption of glycerol and the in-situ Brønsted acid sites for the selective activation of secondary CO bonds, thus largely augmenting the hydrogenolysis performance. This discovery not only provides the new strategy of defect engineering to enhance hydrogenolysis performance of secondary CO bond in biomass compounds, but reveals the unique role of the unsaturated coordination structure of WOx in chemoselective hydrogenolysis reactions. 

Man Yang

Papers

Synthesis, Functional Modifications, and Diversified Applications of Hybrid BiOCl-Based Heterogeneous Photocatalysts: A Review

Facet Junction Engineering for Photocatalysis: A Comprehensive Review on Elementary Knowledge, Facet-Synergistic Mechanisms, Functional Modifications, and Future Perspectives

One-pot construction of Ta-doped BiOCl/Bi heterostructures toward simultaneously promoting visible light harvesting and charge separation for highly enhanced photocatalytic activity

Mechanism Insight into an Unprecedented Dual Series‐Parallel Photocharge Separation in Quaternary Cu2O Facet Junctions

Regulating oxygen defects via atomically dispersed alumina on Pt/WOx catalyst for enhanced hydrogenolysis of glycerol to 1,3-propanediol