Selective Conversion Of CO2 Research Articles

Highly Selective Electrocatalytic CO2 Conversion to Tailored Products through Precise Regulation of Hydrogenation and C-C Coupling.

The electrochemical reduction reaction of carbon dioxide (CO2RR) into valuable products offers notable economic benefits and contributes to environmental sustainability. However, precisely controlling the reaction pathways and selectively converting key intermediates pose considerable challenges. In this study, our theoretical calculations reveal that the active sites with different states of copper atoms (1-3-5-7-9) play a pivotal role in the adsorption behavior of the *CHO critical intermediate. This behavior dictates the subsequent hydrogenation and coupling steps, ultimately influencing the formation of the desired products. Consequently, we designed two model electrocatalysts comprising Cu single atoms and particles supported on CeO2. This design enables controlled *CHO intermediate transformation through either hydrogenation with *H or coupling with *CO, leading to a highly selective CO2RR. Notably, our selective control strategy tunes the Faradaic efficiency from 61.1% for ethylene (C2H4) to 61.2% for methane (CH4). Additionally, the catalyst demonstrated a high current density and remarkable stability, exceeding 500 h of operation. This work not only provides efficient catalysts for selective CO2RR but also offers valuable insights into tailoring surface chemistry and designing catalysts for precise control over catalytic processes to achieve targeted product generation in CO2RR technology.

UiO-n-membrane regulate bifunctional catalysts GaZrOx/SAPO-34@UiO-n improving CO2 conversion to light olefins

Assembling synergistic-functional nanocatalysts is an effective strategy to achieve highly both active and selective conversion of CO2 into light olefins. Herein, the bifunctional GaZrOx/SAPO-34@UIO-n (n = 66, 66-NH2, 67, 67-NH2, 68, 69) catalyst, UiO-n membrane encapsulating monodispersed SAPO-34 zeolite to get the core-shell SAPO-34@UiO-n (S@Un) and then mixed with GaZrOx, is assembled for CO2 hydrogenation to light olefins. The GaZrOx/SAPO-34 shows C2=-C4= selectivity of only 62.1 %, but the selectivity to C2=-C4= reaches 81.8–85.4 % for the GaZrOx/S@Un. Optimizing UiO-n membrane, the GaZrOx/S@U68 exhibits excellent performance for CO2 conversion into light olefins. The selectivity to C2=-C4= reaches 85.4 % at 19.4 % CO2 conversion and 48.1 % CO selectivity. DOS calculations indicates that GaZrOx can effectively promote CO2 hydrogenation. The results reveal the UiO-n membrane-encapsulating-SAPO-34 synergy-enhancing CO2 conversion to light olefins besides the good catalytic matching of GaZrOx to SAPO-34 in the bifunctional catalyst component.

Structure-Function Relationship of p-Block Bismuth for Selective Photocatalytic CO2 Reduction.

Selective photocatalytic reduction of CO2 to value-added fuels, such as CH4, is highly desirable due to its high mass-energy density. Nevertheless, achieving selective CH4 with higher production yield on p-block materials is hindered by non-ideal adsorption of *CHO key intermediate and an unclear structure-function relationship. Herein, we unlock the key reaction steps of CO2 and found a volcano-type structure-function relationship for photocatalytic CO2-to-CH4 conversion by gradual reduction of the p-band center of the p-block Bi element leading to formation of Bi-oxygen vacancy heterosites. The selectivity of CH4 is also positive correlation with adsorption energy of *CHO. The Bi-oxygen vacancy heterosites with an appropriate filled Bi-6p orbital electrons and p band center (-0.64) enhance the coupling between C-2p of *CHO and Bi-6p orbitals, thereby resulting in high selectivity (95.2 %) and productivity (17.4 μmol g-1 h-1) towards CH4. Further studies indicate that the synergistic effect between Bi-oxygen vacancy heterosites reduces Gibbs free energy for *CO-*CHO process, activates the C-H and C=O bonds of *CHO, and facilitates the enrichment of photoexcited electrons at active sites for multielectron photocatalytic CO2-to-CH4 conversion. This work provides a new perspective on developing p-block elements for selective photocatalytic CO2 conversion.

Structure‐Function Relationship of p‐Block Bismuth for Selective Photocatalytic CO2 Reduction

AbstractSelective photocatalytic reduction of CO2 to value‐added fuels, such as CH4, is highly desirable due to its high mass‐energy density. Nevertheless, achieving selective CH4 with higher production yield on p‐block materials is hindered by non‐ideal adsorption of *CHO key intermediate and an unclear structure‐function relationship. Herein, we unlock the key reaction steps of CO2 and found a volcano‐type structure‐function relationship for photocatalytic CO2‐to‐CH4 conversion by gradual reduction of the p‐band center of the p‐block Bi element leading to formation of Bi‐oxygen vacancy heterosites. The selectivity of CH4 is also positive correlation with adsorption energy of *CHO. The Bi‐oxygen vacancy heterosites with an appropriate filled Bi‐6p orbital electrons and p band center (−0.64) enhance the coupling between C‐2p of *CHO and Bi‐6p orbitals, thereby resulting in high selectivity (95.2 %) and productivity (17.4 μmol g−1 h−1) towards CH4. Further studies indicate that the synergistic effect between Bi‐oxygen vacancy heterosites reduces Gibbs free energy for *CO‐*CHO process, activates the C−H and C=O bonds of *CHO, and facilitates the enrichment of photoexcited electrons at active sites for multielectron photocatalytic CO2‐to‐CH4 conversion. This work provides a new perspective on developing p‐block elements for selective photocatalytic CO2 conversion.

Investigation of m- and p-xylene linked bimetallic Ni-cyclam-complexes as potential electrocatalysts for the CO2 reduction

Among the various molecular CO2 reduction catalysts, the [Ni(cyclam)]2+ (Ni-{N4}) complex with its earth-abundant metal center and macrocyclic ligand proved to be efficient for the selective electrochemical conversion of CO2 to CO. In the present study we now connected the two Ni-cyclam units by using para- and meta-xylene as organic linkers attached to the amines of the macrocycle to form the p-{Ni2} andm-{Ni2} complexes, respectively, and test them as catalysts for the electrochemical CO2 reduction reactions. Notably, the p-{Ni2} complex demonstrates a higher faraday efficiency in the electrochemical reduction of CO2 to CO compared to the m-{Ni2} complex. This finding highlights the significant role played by the M-M distance in influencing this catalytic process.

A highly efficient porphyrin-based azo-porous organic polymer for selective CO2 capture and conversion

The greenhouse gas (GHG) emissions from fossil fuel combustion and carbon dioxide (CO2) cause global warming and climate change. In this study, we synthesized three porphyrin-based azo-porous organic polymers (PBPOP1, PBPOP2, and PBPOP3) that enable the capture and one-step conversion of CO2. These catalysts effectively capture the CO2 molecules over N2 in a post-combustion environment. PBPOP3 exhibited an enhanced CO2/N2 selectivity at 313 K, with a value of 534. We characterized the porphyrin-based azo-POPs catalysts using FT-IR, 13C solid-state NMR, XRD, TGA, and HR-FESEM. We evaluated the gas adsorption properties using Brunauer–Emmett–Teller analysis, which included adsorption–desorption isotherms, NLDFT pore-size distribution, and adsorption at 298, 313, and 353 K. The fixation of CO2 with styrene oxide and phenyl glycidyl ether was performed using catalysts for conversion to styrene carbonate (tetra-n-butylammonium bromide was used as a co-catalyst). Thus, our findings can be used for reducing the amount of CO2 gas in the atmosphere by synthesizing porphyrin-based azo-POP catalysts.

Pt-N catalytic centres concisely enhance interfacial charge transfer in amines functionalized Pt@MOFs for selective conversion of CO2 to CH4

Improving ligand-to-active metal charge transfer (LAMCT) by finely tuning the organic ligand is a decisive strategy to enhance charge transfer in metal organic frameworks (MOFs)-based catalysts. However, in most MOFs loaded with active metal catalysts, electron transmission encounters massive obstacle at the interface between the two constituents owing to poor LAMCT. Herein, amines (–NH2) functionalized MOFs (NH2-MIL-101(Cr)) encapsulated active metal Pt nanoclusters (NCs) catalysts are synthesized by the polyol reduction method and utilized for the photoreduction of CO2. Surprisingly, the introduction of –NH2 (electron donating) groups within the matrix of MIL-101(Cr) improved the electron migration through the LAMCT process, fostering a synergistic interaction with Pt. The combined experimental analysis exposed the high number of metallic Pt (Pt0) in Pt@NH2-MIL-101(Cr) catalyst through seamless electron shuttling from N of –NH2 group to excited Pt generating versatile hybrid Pt-N catalytic centres. Consequently, these versatile hybrid catalytic centres act as electro-nucleophilic centres, which enable the efficient and selective conversion of CO bond in CO2 to harvest CH4 (131.0 µmol.g−1) and maintain excellent stability and selectivity for consecutive five rounds, superior to Pt@MIL-101(Cr) and most reported catalysts. Our study verified that the precise tuning of organic ligands in MOFs immensely improves the surface-active centres, electron migration, and catalytic selectivity of the excited Pt NCs catalysts encaged inside MOFs through an improved LAMCT pathway.

Evolution of bismuth electrodes activating electrosynthesis of formate from carbon dioxide reduction

Electrochemical conversion of CO2 into valuable chemicals and fuels has emerged as a promising approach to achieving the net-zero emission target. In this work, bismuth (Bi)-based gas diffusion electrodes (GDEs) are prepared via scalable inkjet printing of the precursor on carbon papers, and subsequent thermal treatment. The optimization of the GDEs aims at the efficient CO2 reduction to formate (HCOO−) with good selectivity and high current density. Ex situ FESEM, XRD, and XPS analyses evidence the morphological and structural transformations of Bi-based catalysts during electrolysis. In situ Raman spectroscopy illustrates the dynamic evolution of the electrocatalysts in a range of potentials. The complete procedure is represented as the transformation of Bi2O3 polyhedral microcrystals to a flower-like assembly of Bi2O2CO3 nanoflakes when exposed to KHCO3 electrolyte under electrochemical conditions, and then to metallic Bi at more negative potentials (< −0.6 V vs. RHE). The evolution of Bi-GDEs confirms that metallic Bi nanostructure provides abundant active sites for selective conversion of CO2 to HCOO−, and is highly promising for applications at industrially relavant scales.

Construction of an Electron Capture and Transfer Center for Highly Efficient and Selective Solar-Light-Driven CO2 Conversion.

Exploring high-efficiency photocatalysts for selective CO2 reduction is still challenging because of the limited charge separation and surface reactions. In this study, a noble-metal-free metallic VSe2 nanosheet was incorporated on g-C3N4 to serve as an electron capture and transfer center, activating surface active sites for highly efficient and selective CO2 photoreduction. Quasi in situ X-ray photoelectron spectroscopy (XPS), soft X-ray absorption spectroscopy (sXAS), and femtosecond transient absorption spectroscopy (fs-TAS) unveiled that VSe2 could capture electrons, which are further transferred to the surface for activating active sites. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT) calculations revealed a kinetically feasible process for the formation of a key intermediate and confirmed the favorable production of CO on the VSe2/PCN (protonated C3N4) photocatalyst. As an outcome, the optimized VSe2/PCN composite achieved 97% selectivity for solar-light-driven CO2 conversion to CO with a high rate of 16.3 μmol·g-1·h-1, without any sacrificial reagent or photosensitizer. This work offers new insights into the photocatalyst design toward highly efficient and selective CO2 conversion.

Non-trivial topological surface states regulation of 1 T-OsCoTe2 enables selective C―C coupling for highly efficient photochemical CO2 reduction toward C2+ hydrocarbons

Despite ongoing research, the rational design of non-trivial topological semimetal surface states for the selective photocatalytic CO2 conversion into valuable products remains full of challenges. Herein, we present the synthesis of lattice-matched 1 T-OsCoTe2 for the photoreduction upgrading of CO2 to tri-carbon (C3) alkane (propane, C3H8) by the integration of experimental work and theory prediction/calculation. Experimental studies suggested a high electron-based selectivity of 71.2 % for C3H8 and an internal quantum efficiency of 54.6 % at 380 nm. In-situ X-ray photoelectron spectroscopy and X-ray absorption fine structure spectroscopy demonstrated that Co and Os atoms coordinated with Te atoms enable an efficient Os―Te―Co electron transfer to activate the generation of *CH3, *CHOCO and *CH2OCOCO. Density functional theory calculations further confirmed Os―Te―Co electron bridging on the improved CO2 conversion kinetics. To our knowledge, this is the first report suggesting the role of Os atoms in accelerating the photocatalytic CO2 conversion activity of the topological semimetal 1 T-OsCoTe2.

Strong electric field at the sharp tips of Cu(OH)2 nanochrysanthemums for selective electrochemical CO2 conversion into ethylene

Electrochemical CO2 reduction reaction (CO2RR) is an attractive approach for the mitigation of CO2 emissions and the production of value-added chemicals. However, it remains a challenge to achieve high selectivity of desirable C2 products like ethylene (C2H4) with high economic value and large market. Herein, we report the fabrication of unprecedented Cu(OH)2 nanochrysanthemums catalyst layer (CL). Interestingly, Cu(OH)2 nanochrysanthemums CL exhibits a C2H4 Faradaic efficiency (FE) of 51.2 ± 0.5% and a FE(C2H4+C2H5OH) of 70.0 ± 0.5% in pH nearly neutral electrolytes. It is worth mentioning that Cu(OH)2 nanochrysanthemums CL achieves the highest FEC2 among documented Cu(OH)2 electrocatalysts. The high FEC2H4 and FEC2 can be attributed to the high electrochemical surface area (ECSA, 21.9 mF/cm2) of Cu(OH)2 nanochrysanthemums. In addition, the wellbalanced hydrophilicity-hydrophobicity of the Cu(OH)2 nanochrysanthemums CL also contributes to the high FEC2H4 and FEC2 by simultaneously satisfying efficient transfer of hydrophobic CO2 and C2H4 as well as hydrophilic H2O and C2H5OH. COMSOL multiphysics simulations and density functional theory (DFT) calculations further suggest that the negatively charged sharp tips of Cu(OH)2 nanochrysanthemums would trigger the accumulation of K+ and offer strong local electric field of 9.8 V/μm, promoting C–C coupling and suppressing hydrogen evolution reaction (HER).

Metal–oxygen hybridization in Agcluster/TiO2 for selective CO2 photoreduction to CH4

Selective photocatalytic reduction of CO2 to CH4 is one of the most efficient ways to achieve carbon neutralization. However, the formation of methane remains a challenge due to the slow multiple-proton-coupled electron transfer process and the involvement of various C1 intermediates. Herein, an Agcluster/TiO2 catalyst with Ag-O hybridization was synthesized by supporting Ag clusters on anatase phase TiO2 microspheres for photocatalytic CO2 methanation. The Agcluster/TiO2 sample presents an electron selectivity of 86 % for CH4 production with a yield of 25.25 μmol g–1 h−1. Mechanistic study reveals that Ag clusters accelerate the separation and migration of photogenerated carriers, and enhance the adsorption of CO2. Moreover, the Ag-O hybridization promotes the multiple-proton–electron coupling transfer process by effectively stabilizing intermediates and facilitating *CO hydrogenation to *CHO, resulting in selective CO2 reduction to CH4. This work provides a new insight into the development of selective photocatalytic conversion of CO2 to methane by constructing supported cluster catalysts.

Electro-assisted photocatalytic reduction of CO2 in ambient air using Ag/TNTAs at the gas-solid interface

The direct conversion of atmospheric CO2 into fuel via photocatalysis exhibits significant practical application value in advancing the carbon cycle. In this study, we established an electro-assisted photocatalytic system with dual compartments and interfaces, and coated Ag nanoparticles on the titanium nanotube arrays (TNTAs) by polydopamine modification. In the absence of sacrificial agent and alkali absorption liquid conditions, the stable, efficient and highly selective conversion of CO2 to CO at the gas-solid interface in ambient air was realized by photoelectric synergy. Specifically, with the assistance of potential, the CO formation rates reached 194.9 μmol h−1 m−2 and 103.9 μmol h−1 m−2 under ultraviolet and visible light irradiation, respectively; the corresponding CO2 conversion rates in ambient air were 30% and 16%, respectively. The excellent catalytic effect is mainly attributed to the formation of P–N heterojunction during the catalytic process and the surface plasmon resonance effect. Additionally, the introduction of solid agar electrolytes effectively inhibits the hydrogen evolution reaction and improves the electron utilization rate. This system promotes the development of photocatalytic technology for practical applications and provides new insights and support for the carbon cycle.

Reversible Carbon Dioxide/Lithium Oxalate Regulation toward Advanced Aprotic Lithium Carbon Dioxide Battery.

Li-CO2 batteries have received significant attention owing to their advantages of combining greenhouse gas utilization and energy storage. However, the high kinetic barrier between gaseous CO2 and the Li2CO3 product leads to a low operating voltage (<2.5 V) and poor energy efficiency. In addition, the reversibility of Li2CO3 has always been questioned owing to the introduction of more decomposition paths caused by its higher charging plateau. Here, a novel "trinity" Li-CO2 battery system was developed by synergizing CO2, soluble redox mediator (2,2,6,6-tetramethylpiperidoxyl, as TEM RM), and reduced graphene oxide electrode to enable selective conversion of CO2 to Li2C2O4. The designed Li-CO2 battery exhibited an output plateau reaching up to 2.97 V, higher than the equilibrium potential of 2.80 V for Li2CO3, and an ultrahigh round-trip efficiency of 97.1 %. The superior performance of Li-CO2 batteries is attributed to the TEM RM-mediated preferential growth mechanism of Li2C2O4, which enhances the reaction kinetics and rechargeability. Such a unique design enables batteries to cope with sudden CO2-deficient environments, which provides an avenue for the rationally design of CO2 conversion reactions and a feasible guide for next-generation Li-CO2 batteries.

Reversible Carbon Dioxide/Lithium Oxalate Regulation toward Advanced Aprotic Lithium Carbon Dioxide Battery

AbstractLi−CO2 batteries have received significant attention owing to their advantages of combining greenhouse gas utilization and energy storage. However, the high kinetic barrier between gaseous CO2 and the Li2CO3 product leads to a low operating voltage (&lt;2.5 V) and poor energy efficiency. In addition, the reversibility of Li2CO3 has always been questioned owing to the introduction of more decomposition paths caused by its higher charging plateau. Here, a novel “trinity” Li−CO2 battery system was developed by synergizing CO2, soluble redox mediator (2,2,6,6‐tetramethylpiperidoxyl, as TEM RM), and reduced graphene oxide electrode to enable selective conversion of CO2 to Li2C2O4. The designed Li−CO2 battery exhibited an output plateau reaching up to 2.97 V, higher than the equilibrium potential of 2.80 V for Li2CO3, and an ultrahigh round‐trip efficiency of 97.1 %. The superior performance of Li−CO2 batteries is attributed to the TEM RM‐mediated preferential growth mechanism of Li2C2O4, which enhances the reaction kinetics and rechargeability. Such a unique design enables batteries to cope with sudden CO2‐deficient environments, which provides an avenue for the rationally design of CO2 conversion reactions and a feasible guide for next‐generation Li−CO2 batteries.

Schottky-Functionalized Type-II heterojunction of Ag/CuNb2O6/g-C3N4: Efficient photoredox capability of CO2 to valuable fuel products via gas phase adsorption

Owing to encyclopedic energy crises and ecological concerns, the conversion of solar energy into sustainable value-added fuel products using a reasonable photocatalyst has received a lot of interest. The crucial challenge of the photoreduction of CO2 into fuel products such as CO and CH4 is the minor output and poor selectivity. Herein, a novel synthesized schottky-functionalized type-II heterojunction, Ag/CuNb2O6/g-C3N4 (Ag/CNO/g-CN), is extensively characterized to provide insights regarding its photocatalytic performance in reducing CO2. More significantly, electron paramagnetic resonance was employed to assist in understanding the inclusion of Schottky-junction and type II heterojunction charge transfer. The CO2 photoreduction to CO (2.78 μmol g−1h−1) with Ag/CNO/g-CN was 5- and 3-fold higher than single CNO and single g-CN, and the CO2 photoreduction to CH4 was 0.15 μmol g−1h−1 under simulated solar irradiation. This enhanced CO2 photoreduction was attributed to the large surface area and type II heterojunction, which promoted the separation as well as the transformation of photoinduced e−/h+ pairs and the superior redox ability of charge carriers. The composite's excellent photocatalytic efficiency towards CO2 was exceptionally enhanced by depositing Ag on CNO/g-CN. This study paves the way for immediate needs to explore the selective conversion of CO2 into CO and CH4 via systematic designing and effective schottky-functionalized type-II heterojunction.

Modulation of active center distance of hybrid perovskite for boosting photocatalytic reduction of carbon dioxide to ethylene

Solar-driven photocatalytic CO2 reduction is an energy-efficient and sustainable strategy to mitigate CO2 levels in the atmosphere. However, efficient and selective conversion of CO2 into multi-carbon products, like C2H4, remains a great challenge due to slow multi-electron-proton transfer and sluggish C-C coupling. Herein, a two-dimensional thin-layered hybrid perovskite is fabricated through filling of oxygen into iodine vacancy in pristine DMASnI3 (DMA = dimethylammonium). The rational-designed DMASnI3(O) induces shrinkage of active sites distance and facilitates dimerization of C-C coupling of intermediates. Upon simulated solar irradiation, the DMASnI3(O) photocatalyst achieves a high selectivity of 74.5%, corresponding to an impressive electron selectivity of 94.6%, for CO2 to C2H4 conversion and an effective C2H4 yield of 11.2 μmol g-1 h-1. In addition, the DMASnI3(O) inherits excellent water stability and implements long-term photocatalytic CO2 reduction to C2H4 in a water medium. This work establishes a unique paradigm to convert CO2 to C2+ hydrocarbons in a perovskite-based photocatalytic system.

Highly selective photoelectrochemical CO2 reduction by crystal phase-modulated nanocrystals without parasitic absorption

Photoelectrochemical (PEC) carbon dioxide (CO2) reduction (CO2R) holds the potential to reduce the costs of solar fuel production by integrating CO2 utilization and light harvesting within one integrated device. However, the CO2R selectivity on the photocathode is limited by the lack of catalytic active sites and competition with the hydrogen evolution reaction. On the other hand, serious parasitic light absorption occurs on the front-side-illuminated photocathode due to the poor light transmittance of CO2R cocatalyst films, resulting in extremely low photocurrent density at the CO2R equilibrium potential. This paper describes the design and fabrication of a photocathode consisting of crystal phase-modulated Ag nanocrystal cocatalysts integrated on illumination-reaction decoupled heterojunction silicon (Si) substrate for the selective and efficient conversion of CO2. Ag nanocrystals containing unconventional hexagonal close-packed phases accelerate the charge transfer process in CO2R reaction, exhibiting excellent catalytic performance. Heterojunction Si substrate decouples light absorption from the CO2R catalyst layer, preventing the parasitic light absorption. The obtained photocathode exhibits a carbon monoxide (CO) Faradaic efficiency (FE) higher than 90% in a wide potential range, with the maximum FE reaching up to 97.4% at -0.2 V vs. reversible hydrogen electrode. At the CO2/CO equilibrium potential, a CO partial photocurrent density of -2.7 mA cm-2 with a CO FE of 96.5% is achieved in 0.1 M KHCO3 electrolyte on this photocathode, surpassing the expensive benchmark Au-based PEC CO2R system.

Influence of Environmental Conditions on Electrocatalytic CO2 Reduction

AbstractIn order to address the greenhouse effect and achieve the artificial carbon cycle, the electrocatalytic reduction reactions offer an effective approach for converting carbon dioxide (CO2) into valuable chemicals. In addition to the rational design of catalyst structure to improve the high selective conversion of CO2, exploring the influence of environmental conditions on the reaction path and product types is one of the keys to realizing the high selective conversion of CO2. In this review, we illustrate the important influence of changes in environmental conditions on the effectiveness of electrocatalytic carbon dioxide reduction reaction (CO2RR) technology from the design of the reactor, the selection of the electrolyte, and the setting of the reaction conditions (pressure, temperature, etc.). Through in‐depth understanding and optimization of these factors, the efficiency and selectivity of the CO2RR can be further improved to promote the development of CO2 conversion technology.

Internal electric field modulation by copper vacancy concentration of cuprous sulfide nanosheets for enhanced selective CO2 photoreduction

Although the internal electric field (IEF) of photocatalysts is acknowledged as a potent driving force for photocharge separation, modulating the IEF intensity to achieve enhanced photocatalytic performances remains a challenge. Herein, cuprous sulfide nanosheets with different Cu vacancy concentration were employed to study IEF modulation and corresponding direct charge transfer. Among the samples, Cu1.8S nanosheets possessed intensified IEF intensity compared with those of Cu2S and Cu1.95S nanosheets, suggesting that an enhanced IEF intensity could be achieved by introducing more Cu vacancies. This intensified IEF of Cu1.8S nanosheets induced numerous photogenerated electrons to migrate to its surface, and the dissociative electrons were then captured by Cu vacancies, resulting in efficient charge separation spatially. In addition, the Cu vacancies on Cu1.8S nanosheets accumulated electrons as active sites to lower the energy barrier of rate-determining step of CO2 photoreduction, leading to the selective conversion of CO2 to CO. Herein, the manipulation of IEF intensity through Cu vacancy concentration regulation of cuprous sulfide photocatalysts for efficient charge separation has been discussed, providing a scientific strategy to rationally improve photocatalytic performances for solar energy conversion.