CO Conversion Rate Research Articles

Conversion of carbon dioxide in atmospheric pressure dielectric barrier discharges with different electrode configurations

The choice of electrode configuration and dielectric material is critical to the discharge process and plasma characteristics of a dielectric barrier discharge (DBD) reactor. In this study, a new electrode configuration of DBD reactor with copper mesh as electrode inserted between dielectrics is proposed, which has a much higher capacitance than the conventional double-dielectric layer DBD reactor. Two materials with different relative dielectric permittivities, alumina and zirconia, are chosen as dielectrics for an experimental comparison of CO2 decomposition. The experimental results show that the conversion rate of CO2 for the reactor with copper mesh inserted between dielectrics are higher than that of the corresponding double dielectric layer reactor under the same discharge power, and the conversion rate of CO2 with zirconia as a dielectric material is higher than the case of alumina as a dielectric. Further analysis of discharge characteristics shows that for the reactor with copper mesh inserted between dielectrics, the applied voltage required for discharge is significantly reduced, the amount of transferred charge is significantly increased, and the number of micro-discharge current pulses as well as the average lifetime during a single voltage cycle are also considerably increased, leading to an increase in the CO2 discharge efficiency and conversion rate.

The bifunctional oxygen carrier K/LayCoxFe1-xO3 for the production of C2–C4 olefins via CO2 hydrogenation

Developing the bifunctional oxygen carrier with excellent oxygen mobility and catalytic activity is the key to chemical looping combustion coupled CO2 hydrogenation to light olefins. In this study, a series of K/LayCoxFe1-xO3 (x = 0, 0.2, 0.4, 0.6, y = 0.2, 0.4, 0.8) with oxygen vacancy-active metal dual active centers were constructed by the Co doping-La defect synergistic strategy to evaluate the oxygen release and catalytic performance. The results indicated that K/La0.4Co0.4Fe0.6O3 had high oxygen mobility, and its reduced state can be directly used for CO2 hydrogenation to light olefins (C2=-C4=). The selectivity of C2=-C4= was close to 30%, and the conversion rate of CO2 was 36%. Combined with various characterizations, the synergy of Co doping and La defects increased the oxygen vacancy and promoted the exsolved CoFe alloy under the reduction induction of chemical looping combustion. In situ DRIFTS reveals the dynamic equilibrium of the Formate-Methoxy mechanism and RWGS-FTS pathway. Oxygen vacancies are found to enhance the conversion of CO2 via the formate pathway, while metal active phases alter the product distribution by changing the evolution of intermediates. The Co7Fe3 and oxygen vacancy on K/La0.4Co0.4Fe0.6O3 promotes the formation of CHx∗ and C–C coupling through various intermediates, improving the selectivity of light olefins.

Highly Selective Transformation of CO2 + H2 into Para-Xylene via a Bifunctional Catalyst Composed of Cr2O3 and Twin-Structured ZSM-5 Zeolite

The abundant C1 source CO2 can be utilized to produce value-added chemicals through hydrogenation technology. A bifunctional catalyst consisting of reducible metal oxide Cr2O3 and acidic zeolite ZSM-5 was designed for the direct conversion of CO2 + H2 into valuable aromatics, especially para-xylene (PX), via the methanol-mediated pathway. The twin structure of ZSM-5 (ZSM-5T), with sinusoidal channels that are predominantly exposed to the external surface, enhances the possibility of the transformation of methanol into PX due to the favorable diffusion dynamic of PX in the sinusoidal channels. Via the bifunctional catalyst Cr2O3&ZSM-5T, a PX selectivity of 28.7% and PX space-time yield (STY) of 2.5 gCH2 h−1 kgcat−1 are achieved at a CO2 conversion rate of 16.5%. Furthermore, we rationally modify the ZSM-5T zeolite via Cu species doping and amorphous SiO2 shell coating (Cu-ZSM-5T@SiO2). After combining with the Cr2O3 catalytic component, the CO2 conversion (18.4%) and PX selectivity (33.8%) are increased to some extent, which systematically increases the STY of PX to 3.0 gCH2 h−1 kgcat−1. The physicochemical property of the acidic zeolite and the corresponding structure-function relationship in enhancing the PX productivity are discovered. Our work provides a novel catalyst design idea to boost PX synthesis performance from CO2 hydrogenation.

Bio‑hydrogen and VFA production from steel mill gases using pure and mixed bacterial cultures

A major source of CO2 emissions is the flaring of steel mill gas. This work demonstrated the enrichment of carboxydotrophic bacteria for converting steel mill gas into volatile fatty acids and H2, via gas fermentation. Several combinations of pure and mixed anaerobic cultures were used as inoculum in 0.5-L reactors, operated at 30 and 60 °C. The process was then scaled up in a 4-L membrane bioreactor, operated for 20 days, at 48 °C. The results showed that the enriched microbiomes can oxidize CO completely to produce H2/H+ which is subsequently used to fix the CO2. At 30 °C, a mixture of acetate, isobutyrate and propionate was obtained while H2 and acetate were the main products at 60 °C. The highest CO conversion and H2 production rate observed in the membrane bioreactor were 29 and 28 mL/LR/h, respectively. The taxonomic diversity of the bacterial community increased and the dominant species was Pseudomonas.

Promotion effects of alkali metals on iron molybdate catalysts for CO2 catalytic hydrogenation

CO2 hydrogenation is an attractive way to store and utilize carbon dioxide generated by industrial processes, as well as to produce valuable chemicals from renewable and abundant resources. Iron catalysts are commonly used for the hydrogenation of carbon oxides to hydrocarbons. Iron-molybdenum catalysts have found numerous applications in catalysis, but have been never evaluated in the CO2 hydrogenation. In this work, the structural properties of iron-molybdenum catalysts without and with a promoting alkali metal (Li, Na, K, Rb, or Cs) were characterized using X-ray diffraction, hydrogen temperature-programmed reduction, CO2 temperature-programmed desorption, in-situ 57Fe Mossbauer spectroscopy and operando X-ray adsorption spectroscopy. Their catalytic performance was evaluated in the CO2 hydrogenation. During the reaction conditions, the catalysts undergo the formation of an iron (II) molybdate structure, accompanied by a partial reduction of molybdenum and carbidization of iron. The rate of CO2 conversion and product selectivity strongly depend on the promoting alkali metals, and electronegativity was identified as an important factor affecting the catalytic performance. Higher CO2 conversion rates were observed with the promoters having higher electronegativity, while low electronegativity of alkali metals favors higher light olefin selectivity.

Improved copper-based catalysts for alcohol-assisted CO2 hydrogenation: A comparative study between novel nano-stabilized and deposition-precipitation method

A growing awareness of the need to control CO2 concentration in atmosphere spurs the demand for novel technologies to convert CO2 to useful chemicals. The conversion of CO2 into high-quality liquid fuel such as methanol is a primary focus, and using active catalysts is the key to achieving successful methanol synthesis from CO2 hydrogenation under mild conditions. A new way of synthesizing catalysts with highly dispersed nano copper particles, as well as the characteristics of the catalysts are reported in this study. This is the first instance of methanol catalysts being prepared using a combination of copolymer of polyethylene glycol and maleic acid (PEG-MA) as a stabilizer and layered hydrotalcite (HTC) as a support material. This resulted in a significant decrease in particle size and exhibited efficient catalytic performance in a 1-butanol promoted CO2 hydrogenation reaction at 170 °C, 3 MPa. The work also confirms the status of Zn as an influential factor for methanol synthesis. The application of ion-exchange process and stabilizers in catalyst preparation process effectively improves the CO2 conversion rate and methanol selectivity, which also inspires the development of catalysts in various fields.

CO2 to Value-Added Chemicals: Synthesis and Performance of Mono- and Bimetallic Nickel–Cobalt Nanofiber Catalysts

In an epoch dominated by escalating concerns over climate change and looming energy crises, the imperative to design highly efficient catalysts that can facilitate the sequestration and transformation of carbon dioxide (CO2) into beneficial chemicals is paramount. This research presents the successful synthesis of nanofiber catalysts, incorporating monometallic nickel (Ni) and cobalt (Co) and their bimetallic blend, NiCo, via a facile electrospinning technique, with precise control over the Ni/Co molar ratios. Application of an array of advanced analytical methods, including SEM, TGA–DSC, FTIR-ATR, XRD, Raman, XRF, and ICP-MS, validated the effective integration and homogeneous distribution of active Ni/Co catalysts within the nanofibers. The catalytic performance of these mono- and bimetallic Ni/Co nanofiber catalysts was systematically examined under ambient pressure conditions for CO2 hydrogenation reactions. The bimetallic NiCo nanofiber catalysts, specifically with a Ni/Co molar ratio of 1:2, and thermally treated at 1050 °C, demonstrated a high CO selectivity (98.5%) and a marked increase in CO2 conversion rate—up to 16.7 times that of monometallic Ni nanofiber catalyst and 10.8 times that of the monometallic Co nanofiber catalyst. This significant enhancement in catalytic performance is attributed to the improved accessibility of active sites, minimized particle size, and the strong Ni–Co–C interactions within these nanofiber structures. These nanofiber catalysts offer a unique model system that illuminates the fundamental aspects of supported catalysis and accentuates its crucial role in addressing pressing environmental challenges.

Optimizing the CO2 conversion for the sustainable production of light olefins using Cu-ZnO-ZrO2/SAPO-34 bifunctional catalysts

This study aims to optimize the operating conditions for one-step carbon dioxide hydrogenation to light olefins using ternary CuZnZr metal oxide and SAPO-34 zeolite catalysts. The catalyst was prepared using hydrothermal and co-precipitation synthesis, and it was characterized using XRD, TEM, BET, SEM, H2-TPR, and NH3-TPD techniques. The impact of temperature, space velocity, and H2/CO2 ratio on CO2 conversion, olefins selectivity, and CO selectivity was studied using response surface methodology (RSM). The desirability function was used to optimize multiple responses in the CO2 hydrogenation process at the same time. It takes into account the lower and upper limits, as well as the targets for each response, and produces a score that can be used to determine the best experimental conditions. It is possible to maximize CO2 conversion and olefin selectivity while minimizing CO selectivity by analyzing the optimal parameters. The optimal conditions were determined to be 375 °C, a space velocity of 9 L/g.h, and an H2/CO2 ratio of 3. The CO2 conversion rate was 16.56%, the olefins selectivity was 77.24%, and the CO selectivity was 67.91% under these conditions. The hybrid catalyst also demonstrated remarkable stability after 100 h of operation without losing activity. The results of the study show that the CuZZ/SAPO-34 catalyst has the potential to effectively reduce CO2 to light olefins under optimized conditions.

Strong photo-thermal coupling effect boosts CO2 reduction into CH4 in a concentrated solar reactor

This study is dedicated to solving the problems of low energy utilization and low yield in the conventional photocatalytic CO2 reduction process. Herein, we constructed a novel concentrated solar (light) reactor and enabled the titanium foam-based monolithic photocatalyst TF@TNT/0.4CoOx-0.1CuO to improve the solar energy utilization efficiency and CO2 conversion rate by concentrating light and its thermal effect. We found that the yield of CH4 increased up to 220 times (from 0.53 µmol/cm2 to 116.4 µmol/cm2) when the light intensity of the reactor was increased from 400 mW/cm2 to 4266 mW/cm2 (10.6 times). Meanwhile, the solar-to-fuel conversion efficiency was improved up to 0.35% in the concentrated solar (light) reactor. We further investigated the origin of the photothermal coupling effect with concentrated light through the electrochemical and photochemical measurements. It shows that the concentrated light can further lower the reaction barrier (from 41.62 to 31.51 kJ/mol) and the induced photothermal coupling effect could significantly increase the yield. This provides a valuable strategy for the efficient and environmentally friendly utilization of CO2 using solar energy.

Boosting oxygen vacancies by modulating the morphology of Au decorated In2O3 with enhanced CO2 hydrogenation activity to CH3OH

CO2 hydrogenation to methanol has become one of the most promising ways for CO2 utilization, however, the CO2 conversion rate and methanol selectivity of this reaction still need to be improved for industrial application. Here we investigated the structure-activity relationship for CO2 conversion to methanol of In2O3-based catalysts by modulating morphology and decorating Au. Three different Au/In2O3 catalysts were prepared, their activity follow the sequence of Au/In2O3-nanosphere (Au/In2O3-NS) > Au/In2O3-nanoplate (Au/In2O3-NP) > Au/In2O3-hollow microsphere (Au/In2O3-HM). Au/In2O3-NS exhibited the best performance with good CO2 conversion of 12.7%, high methanol selectivity of 59.8%, and large space time yield of 0.32 gCH3OH/(hr·gcat) at 300°C. The high performance of Au/In2O3-NS was considered as the presence of Au. It contributes to the creation of more surface oxygen vacancies, which further promoted the CO2 adsorption and facilitated CO2 activation to form the formate intermediates towards methanol. This work clearly suggests that the activity of In2O3 catalyst can be effective enhanced by structure engineering and Au decorating.

The advantage of praseodymium doped TiO2 composite as the support of Au catalysts for CO oxidation in CO2-rich atmosphere

In this study, based on the characteristic of lanthanide in oxygen storage capacity, a series of PraTibOx composite supports with different mole ratios of Pr to Ti and the corresponding Au catalysts were prepared - to investigate the oxidation of CO under CO2-rich atmosphere with lean oxygen content. A significant promotion in CO conversion rate over the catalyst with a molar ratio of Pr:Ti = 1:2 and a very high catalytic stability was also obtained. The addition of optimal Pr will make smaller gold particles, provide higher capacity in surface reactive oxygen releasing at low temperatures and weaken the deposition of carbonates in CO2-rich atmosphere. However, more Pr will strongly interact with gold, which leads to the majority of Au+ species in the catalysts and thus lower the catalytic activity. This study may provide a potential application of rare earth elements in sealed CO2-laser.

Constructing Nanocaged Enzymes for Synergistic Catalysis of CO2 Reduction.

Promoting the activity of biological enzymes under in vitro environment is a promising technique for bioelectrocatalytic reactions, such as the conversion of carbon dioxide (CO2 ) into valuable chemicals, which is a promising strategy to address the environmental issue of CO2 in the atmosphere; however, this technique remains challenging. Herein, a nanocage structure for enzyme confinement is synthesized to enable the in situ encapsulation of formate dehydrogenase (FDH) in a porous metal-organic framework, which acts as a coenzyme and boosts the hybrid synergistic catalysis using enzymes. This study reveals that the synthesized FDH@ZIF-8 nanocage-structured hybrid (CSH) catalyst exhibits an improved catalytic ability of the enzymes and increases the hydrophobicity of the electrode and its affinity to CO2 . Thus, CSH can trap CO2 and control its microenvironments. The CSH catalyst boosts the conversion rate of CO2 to formic acid (HCOOH) to 28 times higher than that when using pure FDH. The in situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) spectra indicates that OCHO* is the key intermediate. Density functional theory (DFT) calculations show that CSH has extremely low overpotential and is particularly effective for producing formate. This protection architecture for enzymes considerably promotes their biological application under in vitro environments.

Microbial Electrochemical CO2 Reduction and In-Situ Biogas Upgrading at Various pH Conditions

Microbial electrochemical CO2 reduction and in-situ biogas upgrading can effectively reduce the CO2 content in biogas produced during anaerobic digestion, thereby reducing CO2 emissions and achieving carbon reduction. pH is an important indicator in this process as it can significantly change the solubility and forms of CO2 in the aquatic phase. This study comprehensively evaluated the optimal pH value from the perspectives of methane upgrading performance and electron utilization efficiency and observed and analyzed the morphology of the biofilm on the electrode surface and the microbial community in the cathodic region under optimal conditions. The results showed that the optimal pH was 6.5; methane content reached ~88.3% in the biogas; methane production reached a maximum of 22.1 ± 0.1 mmol·d−1, with an increase in methane production compared to the control group reaching a maximum of 1.7 mmol·d−1; and CO2 conversion rate reached ~22.9%. A dense biofilm with a thickness of 51.3 μm formed on the electrode surface, with Methanobacterium being the dominant genus, with a high relative abundance of 69.3%, and Geobacter had a relative abundance of 20.1%. The above findings have important guiding significance for the practical application of methane upgrading.

Highly Dispersed and Stable Ni/SiO2 Catalysts Prepared by Urea-Assisted Impregnation Method for Reverse Water–Gas Shift Reaction

The nickel-based catalyst was more active in the reverse water-gas shift reaction, but it is easy to sinter and deactivate in high temperature reaction (≥600 °C). A urea-assisted impregnation method was utilized to create a Ni/SiO2-N catalyst to increase the catalytic stability of Ni-based catalysts. For at least 20 h, the Ni/SiO2-N catalyst in the reverse water-gas shift process at 700 °C remained stable, and in the high temperature RWGS reaction, the conversion rate of CO2 of the catalyst is close to the equilibrium conversion rate. The catalysts were characterized by BET, XRD, H2-TPR, and TEM, and the results demonstrate that the Ni particles had a small particle size and exhibited strong interaction with the SiO2 support in the Ni/SiO2-N catalyst, which led to the catalyst’s good activity and stability. Urea-assisted impregnation is a facile method to prepare stable Ni/SiO2 catalysts with high Ni dispersion.

Highly efficient catalytic CO oxidation by balancing the crystal and mesoporous structure of Ta2O5 carrier combined with cobalt

Because the combination of Co and common support (Al, Ti, et al.) usually shows poor catalytic activity, tantalum has been introduced for CO conversion as a novel carrier due to the excellent performance. In this work, Co3O4 was loaded on four forms of tantalum support (amorphous, mesoporous, crystalline and crystalline mesoporous, abbreviated as Co/Ta-am, Co/Ta-me, Co/Ta-cry and Co/Ta-cm, respectively). And among these four states, Co/Ta-cm presents the highest CO conversion rate. The temperature of 90% CO conversion rate of Co/Ta-cm is approximately 130 ℃ at the high space velocity of 780,000 h−1, which is 70%, 82% and 88% higher than that of Co/Ta-cry, Co/Ta-me and Co/Ta-am, respectively. Moreover, the characteristics of the catalyst have been studied by XRD, SEM, BET, TGA, and H2-TPR, and the results reveal that Co/Ta-cm has the excellent crystallinity and stability, and the morphology is regular. X-ray photon spectroscopy and in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) have been performed to investigate the reaction mechanism, which indicates that Co3+ is the active component and lattice oxygen plays a critical role in CO oxidation.

Synthetic Ni–CaO–CeO2 dual function materials for integrated CO2 capture and conversion via reverse water–gas shift reaction

Integrated CO2 capture with reverse water gas shift (RWGS) reaction to produce syngas represents a promising technology to realize C1 recycling and utilization. Designing highly efficient Ni–CaO dual function materials (DFMs) is the key to achieve integrated CO2 capture and utilization (ICCU). In this work, Ni–CaO–CeO2 DFMs powders and pellets are prepared by the wet mixing, coprecipitation and sol–gel methods using acetate and nitrate precursors. Physicochemical properties and ICCU performance of the Ni–CaO–CeO2 DFMs depend on synthetic mode, precursor, and granulation process. NiCaCe-SG (A) and NiCaCe-SG (N) prepared by sol–gel method show excellent ICCU-RWGS performance due to the developed pore structures, enhanced surface basicity, uniform Ni dispersion, minimized Ni grain size, abundant oxygen vacancies and reinforced reducibility. The NiCaCe-SG (A) sample prepared using acetate salts as precursors exhibits better ICCU-RWGS performance than the nitrate precursors-derived NiCaCe–SG (N) DFMs. Granulation adversely affects the CO2 capture capacity, CO yield and working stability of the NiCaCe–SG (N) sample due to declined textural properties, weakened surface basicity and reducibility. NiCaCe–SG (A) represents an excellent DFMs candidate for ICCU-RWGS with high CO2 uptake and conversion rate of 15.34 mmol CO2/g and 92.4 %, great CO yield and CO selectivity of 5.97 mmol CO/g and 89.1 %, and good working stability (a low decay rate of 11.6 % in 10 cycles). These results have provided new insights into the rational design of high-performance DFMs for ICCU applications.

Large-Scale Synthesis of Multifunctional Single-Phase Co2 C Nanomaterials.

Achieving scalable synthesis of nanoscale transition-metal carbides (TMCs), regarded as substitutes for platinum-group noble metals, remains an ongoing challenge. Herein, a 100-g scale synthesis of single-phased cobalt carbide (Co2 C) through carburization of Co-based Prussian Blue Analog (Co-PBA) is reported in CO2 /H2 atmosphere under mild conditions (230 °C, ambient pressure). Textural property investigations indicate a successful preparation of orthorhombic-phased Co2 C nanomaterials with Pt-group-like electronic properties. As a demonstration, Co2 C achieves landmark photo-assisted thermal catalytic CO2 conversion rates with photo-switched product selectivity, which far exceeds the representative Pt-group-metal-based catalysts. This impressive result is attributed to the excellent activation of reactants, colorific light absorption, and photo-to-thermal conversion capacities. In addition to CO2 hydrogenation, the versatile Co2 C materials show huge prospects in antibacterial therapy, interfacial water evaporation, electrochemical hydrogen evolution reaction, and battery technologies. This study paves the way toward unlocking the potential of multi-functional Co2 C nanomaterials.

Gas penetrating hollow fiber Bi with contractive bond enables industry-level CO2 electroreduction

Electrochemical conversion of carbon dioxide (CO2) to valuable fuels driven by renewable electricity exhibits significant potential for achieving carbon neutrality. Bismuth (Bi) possesses the reliable capability of electrocatalyzing CO2 to formate, and high formate faradaic efficiencies have been realized over Bi-based catalysts, but industry-level large current densities with high conversion rates at mild conditions remain challenging yet. Herein we present a bismuth hollow fiber (Bi HF) as a gas penetration electrode (GPE) that efficiently reduces CO2 with a formate faradaic efficiency of 93% and a current density of 1.13 A cm−2 at − 1.26 V (vs. RHE), corresponding to a CO2 conversion rate of 37% under ambient temperature and pressure. Finite element analysis (FEA) and density functional theory (DFT) demonstrate that the synergetic combination of unlimited CO2 feeding to triphasic interface reactions and selective reduction induced by contractive Bi-Bi bond is responsible for the superior activity of Bi HF.

Zn-CdZrOx solid solution catalysts for hydrogenation of CO2 to methanol

CO2 is one of the members of greenhouse gases, and its capture, collection, and recycling have aroused widespread concern. Methanol is not only a basic organic chemical raw material, but also a high-quality clean fuel. The idea of CO2 hydrogenation to methanol can turn waste into treasure and realize the resource utilization of CO2 ultimately. Of course, the value of solving environmental and energy problems is immeasurable.Here, a series of y% Zn-doped CdZrOx catalysts are prepared and the 5.0% Zn-CdZrOx shows 80.82% methanol selectivity and 8.52% CO2 conversion rate at 320℃. Combining HRTEM images and XRD patterns, it is found that 5% Zn-CdZrOx shows the structure of the solid solution. CO2-TPD shows that the desorption peak area of 5.0% Zn-CdZrOx is large, which means more beneficial to CO2 adsorption and activation. H2-TPR indicates the existence of the strongly synergistic interaction between Zn, Cd, and Zr of 5.0% Zn-CdZrOx. From the in-situ DRIFTS, the peaks of HCOO* and H3CO* species are monitored, which is important to methanol formation.It is supposed there is a synergistic effect between Cd, Zn, and Zr in this catalyst and the structure of the solid solution is the decisive factor for the activity of CO2 hydrogenation to methanol.

Build-in electric field in CuWO4/covalent organic frameworks S-scheme photocatalysts steer boosting charge transfer for photocatalytic CO2 reduction

Covalent organic frameworks (COFs) are crystalline porous materials with enormous potential for realizing solar-driven CO2-to-fuel conversion, yet the sluggish transfer/separation of photoinduced electrons and holes remains a compelling challenge. Herein, a step (S)-scheme heterojunction photocatalyst (CuWO4-COF) was rationally fabricated by a thermal annealing method for boosting CO2 conversion to CO. The optimal CuWO4/COF composite sample, integrating 10 wt% CuWO4 with an olefin (C═C) linked COF (TTCOF), achieved a remarkable gas–solid phase CO yield as high as 7.17 ± 0.35 μmol g−1h−1 under visible light irradiation, which was significantly higher than the pure COF (1.6 ± 0.29 μmol g−1h−1). The enhanced CO2 conversion rate could be attributable to the interface engineering effect and the formation of internal electric field (IEF) directing from TTCOF to CuWO4 according to the theoretical calculation and experimental results, which also proves the electrons transfer from TTCOF to CuWO4 upon hybridization. In addition, driven by the IEF, the photoinduced electrons can be steered from CuWO4 to TTCOF under visible light irradiation as well-elucidated by in-situ irradiated X-ray photoelectron spectroscopy, verifying the S-scheme charge transfer pathway over CuWO4/COF composite heterojunctions, which greatly foster the photoreduction activity of CO2. The preparation technique of the S-scheme heterojunction photocatalyst in this study provides a paradigmatic protocol for photocatalytic solar fuel generation.