Photocatalytic Reduction Of Carbon Dioxide Research Articles

Hybrid Photocatalyst Constructed Using Polymerized Metal Complexes and Semiconductor Powders for Photocatalytic Carbon Dioxide Reduction

Hybrid Photocatalyst Constructed Using Polymerized Metal Complexes and Semiconductor Powders for Photocatalytic Carbon Dioxide Reduction

2D/1D nested hollow porous ZnIn2S4/g-C3N4 heterojunction based on morphology modulation for photocatalytic CO2 reduction

The two-dimensional (2D) composite one-dimensional (1D) heterojunction structure is one of the main strategies for constructing composite photocatalysts for photocatalytic reduction of carbon dioxide (CO2). However, morphology modulation for 2D/1D heterojunction is an important way to enhance performance. In this study, a unique 2D/1D ZnIn2S4/g-C3N4 nested hollow porous heterojunction structure was constructed by an in-situ growth method with spatial confinement effect. The synergy between 1D g-C3N4 and 2D ZnIn2S4, achieved through advanced morphology modulation at an optimal ratio of 3:1, results in the formation of the CZ-3 photocatalyst. This unique configuration enables a simultaneous high yield of carbon monoxide (CO) and methane (CH4), achieving 79.96 μmol/g and 17.33 μmol/g respectively, under visible light irradiation without the need for sacrificial agents. The core of this enhanced photocatalytic performance is attributed to the employment of a type-II heterojunction mechanism, which optimizes the transfer of photogenerated carriers. Ultraviolet-visible diffuse reflection spectrum, photoluminescence spectrum and photoelectrochemical analysis reveal the effect of morphology on photocatalytic performance in terms of visible light absorption, photogenerated carrier pairs separation and electronic band structure of heterojunction. By combining the advantages of 2D/1D structural benefits with the efficient charge dynamics of a type-II heterojunction, this work provides new ideas for improving the morphology of composite heterojunction photocatalysts with 2D/1D structure to enhance the photocatalytic CO2 reduction performance.

Photocatalytic CO2 Reduction Using an Osmium Complex as a Panchromatic Self‐Photosensitized Catalyst: Utilization of Blue, Green, and Red Light

AbstractThe photocatalytic reduction of carbon dioxide (CO2) represents an attractive approach for solar‐energy storage and leads to the production of renewable fuels and valuable chemicals. Although some osmium (Os) photosensitizers absorb long wavelengths in the visible‐light region, a self‐photosensitized, mononuclear Os catalyst for red‐light‐driven CO2 reduction has not yet been exploited. Here, we discovered that the introduction of an Os metal to a PNNP‐type tetradentate ligand resulted in the absorption of light with longer‐wavelength (350–700 nm) and that can be applied to a panchromatic self‐photosensitized catalyst for CO2 reduction to give mainly carbon monoxide (CO) with a total turnover number (TON) of 625 under photoirradiation (λ≥400 nm). CO2 photoreduction also proceeded under irradiation with blue (λ0=405 nm), green (λ0=525 nm), or red (λ0=630 nm) light to give CO with >90 % selectivity. The quantum efficiency using red light was determined to be 12 % for the generation of CO. A catalytic mechanism is proposed based on the detection of intermediates using various spectroscopic techniques, including transient absorption, electron paramagnetic resonance, and UV/Vis spectroscopy.

Photocatalytic CO2 Reduction Using an Osmium Complex as a Panchromatic Self-Photosensitized Catalyst: Utilization of Blue, Green, and Red Light.

The photocatalytic reduction of carbon dioxide (CO2) represents an attractive approach for solar-energy storage and leads to the production of renewable fuels and valuable chemicals. Although some osmium (Os) photosensitizers absorb long wavelengths in the visible-light region, a self-photosensitized, mononuclear Os catalyst for red-light-driven CO2 reduction has not yet been exploited. Here, we discovered that the introduction of an Os metal to a PNNP-type tetradentate ligand resulted in the absorption of light with longer-wavelength (350-700 nm) and that can be applied to a panchromatic self-photosensitized catalyst for CO2 reduction to give mainly carbon monoxide (CO) with a total turnover number (TON) of 625 under photoirradiation (λ≥400 nm). CO2 photoreduction also proceeded under irradiation with blue (λ0=405 nm), green (λ0=525 nm), or red (λ0=630 nm) light to give CO with >90 % selectivity. The quantum efficiency using red light was determined to be 12 % for the generation of CO. A catalytic mechanism is proposed based on the detection of intermediates using various spectroscopic techniques, including transient absorption, electron paramagnetic resonance, and UV/Vis spectroscopy.

Engineering Photothermal Catalytic CO2 Nanoreactor for Osteomyelitis Treatment by In Situ CO Generation.

Photocatalytic carbon dioxide (CO2) reduction is an effective method for in vivo carbon monoxide (CO) generation for antibacterial use. However, the available strategies mainly focus on utilizing visible-light-responsive photocatalysts to achieve CO generation. The limited penetration capability of visible light hinders CO generation in deep-seated tissues. Herein, a photothermal CO2 catalyst (abbreviated as NNBCs) to achieve an efficient hyperthermic effect and in situ CO generation is rationally developed, to simultaneously suppress bacterial proliferation and relieve inflammatory responses. The NNBCs are modified with a special polyethylene glycol and further embellished by bicarbonate (BC) decoration via ferric ion-mediated coordination. Upon exposure to 1064nm laser irradiation, the NNBCs facilitated efficient photothermal conversion and in situ CO generation through photothermal CO2 catalysis. Specifically, the photothermal effect accelerated the decomposition of BC to produce CO2 for photothermal catalytic CO production. Benefiting from the hyperthermic effect and in situ CO production, in vivo assessments using an osteomyelitis model confirmed that NNBCs can simultaneously inhibit bacterial proliferation and attenuate the photothermal effect-associated pro-inflammatory response. This study represents the first attempt to develop high-performance photothermal CO2 nanocatalysts to achieve in situ CO generation for the concurrent inhibition of bacterial growth and attenuation of inflammatory responses.

Constructing cuprous oxide-modified zinc tetraphenylporphyrin ultrathin nanosheets heterojunction for enhanced photocatalytic carbon dioxide reduction to methane

The application of supermolecular naonostructures in the photocatalytic carbon dioxide reduction reaction (CO2RR) has attracted increasing attentions. However, it still faces significant challenges, such as low selectivity for multi-electron products and poor stability. Here, the cuprous oxide (Cu2O)-modified zinc tetraphenylporphyrin ultrathin nanosheets (ZnTPP NSs) are successfully constructed through the aqueous chemical reaction. Comprehensive characterizations confirm the formation of type-II heterojunction between Cu2O and ZnTPP in Cu2O@ZnTPP, and the electron transfer from Cu2O to ZnTPP through the Zn-O-Cu bond under the static contact. Under the visible-light irradiation (λ > 420 nm), the optimized Cu2O@ZnTPP sample as catalyst for photocatalytic CO2RR exhibits the methane (CH4) evolution rate of 120.9 μmol/g/h, which is ∼ 4 and ∼ 10 times those of individual ZnTPP NSs (28.0 μmol/g/h) and Cu2O (12.8 μmol/g/h), respectively. Meanwhile, the CH4 selectivity of ∼ 98.7 % and excellent stability can be achieved. Further experiments reveal that Cu2O@ZnTPP has higher photocatalytic conversion efficiency than Cu2O and ZnTPP NSs, and the photoinduced electron transfer from ZnTPP to Cu2O can be identified via the path of ZnTPP→ (ZnTPP•ZnTPP)*→ ZnTPP-→ Zn-O-Cu → Cu2O. Consequently, Cu2O@ZnTPP exhibits a shorter electron-hole separation lifetime (3.3 vs. 9.3 ps) and a longer recombination lifetime (23.1 vs. 13.4 ps) than individual ZnTPP NSs. This work provides a strategy to construct the organic nanostructures for photocatalytic CO2RR to multi-electron products.

Spiral-template from waste tea-leaf to design hierarchical dispersed zinc oxide nanocatalyst for boosting their photocatalytic carbon dioxide reduction

The utilization of cellulose-based templates to enhance the dispersion of zinc oxide (ZnO) nanoparticles represents an effective approach for enhancing their photocatalytic carbon dioxide (CO2) reduction activity. However, the limited availability of surface active sites on linear cellulose fiber has posed a significant challenge for loading ZnO nanoparticles. The present study introduces a technique for segregating spiral vessel (SV) from waste tea-leaves and employing them as templates for in-situ self-assembled ZnO nanoparticles. Due to the inherent three-dimensional (3D) stability of the spiral structure, ZnO nanoparticles exhibit excellent dispersion and maintain a stable hierarchical spiral morphology even after template removal. With the help of a field emission scanning electron microscope (FE-SEM), it could be observed that SV-loaded ZnO nanospheres extracted from waste Pu 'er tea-leaves retained the best spiral morphology after removing the template. The photocatalytic CO2 conversion over spheroidal ZnO with SV as templates (ZnOSS) significantly enhanced yields of CO and CH4, reaching 6.700 and 1.666 μmol·g−1h−1, respectively, surpassing those of other synthesized catalysts. The results obtained from the free radical scavenging experiment and electron paramagnetic resonance (EPR) test demonstrate the pivotal involvement of superoxide radicals (∙O2−) and hydroxyl radicals (∙OH) in the photocatalytic reduction of CO2. Quantum mechanical simulation further verified that the ZnO (0 0 2) crystal face was the best reaction interface with CO2. The design of a cellulose-based spiral template not only facilitates the valorization of waste biomass but also offers a novel perspective for the synthesis of efficient photocatalysts.

N-doped carbon-supported Cu–CuO nanoparticles for photocatalytic reduction of carbon dioxide

Value-added conversion of CO2 using solar energy is a sustainable strategy to address the energy crisis and environmental issues simultaneously. In this work, Cu–CuO/NC catalysts were successfully prepared by a sol-gel method, and the effects of Cu doping ratio and heat treatment temperature on the catalyst properties were investigated. The experimental results revealed that 7%CNC-600 °C has the best photocatalytic reduction performance of CO2 to CH3OH within 8h, 812μmol/gcat. The catalysts were also analyzed using techniques such as XRD, SEM, TEM, Raman spectroscopy, CO2-TPD, PL, etc. The superior catalytic activity mainly benefits from the electron capture properties of the metal and its synergistic effect with nitrogen-doped carbon, resulting in a significantly improved catalyst optical property, enhanced CO2 adsorption capacity, and improved separation efficiency of photoexcited charges. Furthermore, the combined DRS and VB-XPS results elucidate the photocatalytic reaction mechanism. This study could provide potential strategies for environmental purification and energy conversion.

Mechanistic exploration in controlling the product selectivity via metals in TiO2 for photocatalytic carbon dioxide reduction

Harnessing the power of the sun, the photocatalytic CO2 reduction process emerges as a pivotal sustainable solution, utilizing solar energy a premier, clean energy source known for its efficiency and economic viability in the current energy paradigm. This study investigates the impact of metals (Cu, Ag, Au) on enhancing the photocatalytic CO2 reduction capabilities of TiO2. In-depth mechanistic analysis conducted using in-situ DRIFTS for identifying the key reaction intermediates, highlights that the catalytic performance, both in terms of activity and product selectivity, is tightly linked to the underlying reaction mechanisms route, optoelectronic properties, and substrate’s (CO2 and H2O) affinities to the catalyst surface. Enhanced light absorption and reduced charge recombination (lifetime enhancement from 0.21 ns to ∼1.2 ns) in case of metal incorporated resulted in enhanced overall photocatalytic performance. With Au as dopant, demonstrated highest electron selectivity for H2 (>97%) compared to Ag and Cu, which showed relatively higher CO2 reduction electron selectivity (∼20% for Cu). The study reveals the crucial interplay of intermediate stabilization, demonstrating its critical role in governing the reaction pathways i.e., carbene or formaldehyde routes as observed in case of Ag and Cu respectively and thus the specific final products. For enhancing the selectivity of CO, engineering the catalyst surface to favour weak CO adsorption is vital. Observations in the CO-TPD measurements demonstrated that Ag sites were effective in promoting the weaker CO* stabilization thus displayed more selectivity towards CO as compared to Cu. While higher CH3OH formation rates in case of Cu, were found to be related to the augmented reactive M=O species stabilization which promotes the oxidation of CH4 to CH3OH. Additionally, in case of Cu, the CH3O* intermediates stabilized effectively, which contributed to more Methanol selectivity through favoured formaldehyde route. While in case of Ag, the CH2* stabilization suggests more probability of the carbene pathway in comparison to the formaldehyde route (as in case of Cu) for producing the CH4 as the final hydrogenated C1 product. These insights guide the strategic design of catalysts for controlling the reaction pathways and thus selective C1 product production in photocatalytic CO2 reduction, offering insights for advanced catalyst design.

Enhanced photocatalytic CO2 reduction via single-atom Au anchored on ZnIn2S4 nanosheets

In this study, we systematically investigated the effect of single-atom gold (Au) loaded on ZnIn2S4 nanosheets on the photocatalytic reduction of carbon dioxide (CO2). Utilizing a photodeposition method, we successfully dispersed single-atom Au uniformly on the surface of ZnIn2S4 nanosheets. Under simulated sunlight irradiation, the Au-loaded catalyst demonstrated a higher yield and selectivity in the CO2 reduction reaction compared to the pure ZnIn2S4 nanosheets. Surface photovoltage testing revealed that the addition of Au significantly enhanced the separation efficiency of photo-generated charge carriers, thereby improving the photocatalytic efficiency. Density functional theory calculations indicated that the loading of single-atom Au reduced the reaction energy barrier from CO2 to CO, enhancing the selectivity of photocatalytic CO2 reduction. This research not only developed an efficient catalyst for CO2 reduction but also provided deep insights into the mechanism of single-atom catalysts in the photocatalytic CO2 reduction process through extensive experimental and theoretical analysis.

BiOCl/BiOBr composites for efficient photocatalytic carbon dioxide reduction

BiOBr (BOB) photocatalysts have low photocatalytic CO2 reduction performance due to their low electron-hole pair separation efficiency. To improve this problem, BiOCl (BOCl) is used as a co-catalyst. BOCl is loaded into BOB to form BiOCl/BiOBr (BOCl/BOB) type Ⅰ heterojunction, which enhances the photocatalytic CO2 reduction performance of BOB by promoting the separation of photogenerated electrons and holes. The results of TPR and PL experiments show that the 20% BOCl/BOB composites have the highest photogenerated carrier separation rate, and the results of CO2 reduction experiments show that 20% BOCl/BOB composites have the best photocatalytic CO2 reduction performance of 7.353 μmolg−1h−1, which is 3.22 and 1.99 times higher than pure BOB and BOCl, respectively. This work provides an effective reference for the development of modified photocatalysts.

Recent Progress on the Surface and Bulk Modification of Carbon Nitrides for Photocatalytic Carbon Dioxide Reduction

Photocatalytic CO2 reduction has been considered as a green and sustainable approach to solve energy and environmental problems. However, the CO2 reduction efficiency of various types of semiconductor photocatalysts studied at this stage is far from realizing practical applications. The challenge of photocatalytic CO2 reduction is to design photocatalysts with excellent catalytic performance. This article summarizes the carbon nitride materials for efficient CO2 reduction and obtaining high value‐added products. The physicochemical properties of carbon nitride materials are discussed in terms of the photocatalytic mechanisms (bandgap tuning, high specific surface area, shorter electron–hole transmission paths, increasing the number of active sites, etc.). The present review provides the latest research progress of carbon nitride modification strategies. The prospects and challenges for the application of carbon nitride materials for CO2 reduction are presented. This review article will provide useful guidance for further research on carbon nitride materials for efficient photocatalytic CO2 reduction.

Titanium carbide sealed cadmium sulfide quantum dots on carbon, oxygen-doped boron nitride for enhanced and durable photochemical carbon dioxide reduction

Despite great efforts that have been made, photocatalytic carbon dioxide (CO2) reduction still faces enormous challenges due to the sluggish kinetics or disadvantageous thermodynamics. Herein, cadmium sulfide quantum dots (CdS QDs) were loaded onto carbon, oxygen-doped boron nitride (BN) and encapsulated by titanium carbide (Ti3C2, MXene) layers to construct a ternary composite. The uniform distribution of CdS QDs and the tight interfacial interaction among the three components could be achieved by adjusting the loading amounts of CdS QDs and MXene. The ternary 100MX/CQ/BN sample gave a productive rate of 2.45 and 0.44 μmol g-1 h−1 for carbon monoxide (CO) and methane (CH4), respectively. This CO yield is 1.93 and 6.13 times higher than that of CdS QDs/BN and BN counterparts. The photocatalytic durability of the ternary composite is significantly improved compared with CdS QDs/BN because MXene can protect CdS from photocorrosion. The characterization results demonstrate that the excellent CO2 adsorption and activation capabilities of BN, the visible light absorption of CdS QDs, the good conductivity of MXene and the well-matched energy band alignment jointly promote the photocatalytic performance of the ternary catalyst.

A quadruple transition metal dichalcogenide for variously synergetic electron behaviors during photocatalytic carbon dioxide reduction

A quadruple 2H transition metal dichalcogenide of platinum doped molybdenum selenide sulfide (MoSSe) has been achieved. The critical doping amount of Pt is estimated to be approximately 0.9 a.t.% to prevent the formation of a heterogeneous phase. It has been observed that the excess Pt beyond this critical doping level cannot be settled into the lattice of MoSSe but forms an independent metal phase of Pt nanoparticles, composing a heterostructure with MoSSe, in which the behavior of photogenerated electrons will be predominantly governed by metal Pt and transported along the pathways for gas production in the photocatalytic CO2 reduction. However, as long as Pt can be located in the lattice of MoSSe, the elemental variety of Pt doped MoSSe has provided various active sites during the photocatalytic CO2 reduction process, favoring the localized coupling of matching intermediates, consequently enhancing the production of high value-added liquid products. In essence, the successful integration of Pt into the 2H MoSSe lattice opens up diverse active sites, optimizing the photocatalytic performance on the selectivity of liquid production reduced from CO2.

Strategies to Improve the Activity of Silver–loaded Calcium Titanate Crystal Photocatalyst for Photocatalytic Reduction of Carbon Dioxide with Water

AbstractThe rapid increase of carbon dioxide (CO2) in the atmosphere has sparked a global enthusiasm for carbon recycling. Photocatalytic CO2 reduction with water into carbon–containing products has attracted much attention since it can convert solar energy to the chemical potential of the products and CO2 to valuable compounds at the same time. One of the main products in the photocatalytic reaction system is carbon monoxide (CO), a useful compound for the one‐carbon chemistry and related ones. The current shortage of this system is the low production efficiency, demanding us to improve the activity of the photocatalyst. In this perspective article, by taking a calcium titanate (CaTiO3, CTO) photocatalyst with silver cocatalyst (Ag/CTO) and so on as examples that can promote the selective photocatalytic CO2 reduction with water, we shortly review some strategies to improve the photocatalytic activity such as fabrication of well–structured crystal photocatalysts, development of the surface property and cocatalyst, improvement of surface CO2 adsorption, and improvement of photoabsorption. These concepts will be widely applied and contribute to further development of photocatalytic systems.

Synergistic promotion for the performance of photocatalytic carbon dioxide reduction by vacancy engineering and N-doped carbon nanotubes

The structural devise of photocatalytic materials are closely related to the separation of photogenerated carriers and the transport of charge, which is crucial to enhance the performance of photocatalytic carbon dioxide reduction reaction (CO2RR). Here, a photocatalyst (CdS-SV@Co@NCNT) has been successfully prepared by growing cadmium sulfide nanoparticles with sulfur vacancies on N-doped carbon nanotubes through a simple solvothermal method. The intrinsic electronic structure is regulated by sulfur vacancies to promote photocatalytic activity. Meanwhile, a larger specific surface area of Co@NCNT could expose more reaction sites and shorten the transfer distance of photogenerated carriers. Furthermore, the combination with Co@NCNT could effectively suppress the photocorrosion of CdS. The possible photocatalytic CO2RR path is further speculated by in-situ infrared test results, in which CO2 molecules adsorbed on sulfur vacancies preferentially generate important intermediate COOH*, which is then reduced to CO and CH4. Therefore, it exhibits a high CO yield of 263.3 μmol·g−1·h−1 and trace of CH4 while showing excellent stability. This research provides a novel idea for designing the photocatalysts with highly active and stability for CO2RR.

Nanoflower-like TiO2/CoAl-layered double hydroxide direct Z-scheme for boosted photocatalytic CO2 conversion

Direct Z-scheme heterojunction (DZH) has promising potential in photocatalytic carbon dioxide reduction (PCR) owing to its unusual charge transfer pathway, exceptional charge separation efficiency, and high redox ability. Herein, ultrathin TiO2 nanosheets (NSs) have been employed as a substrate for the in-situ growth of CoAl layered double hydroxide (LDH) NSs to fabricate nanoflower-like TiO2/CoAl-LDH (TCA) DZH. The unconsolidated heterostructure is beneficial for active site exposure and mass transfer, and the inherent alkalinity of CoAl-LDH promoted the adsorption of CO2, synergistically boosting the process of PCR reaction in the TCA system. Simulated calculation and in-situ analysis jointly demonstrate the unique electron transfer processes during hybridization and photoexcitation. The resulting (-)TiO2/(+)CoAl-LDH interfacial electric field and DZH further lead to efficient separation of photogenerated charges of TCA. In the solid–gas system, the optimized TCA heterojunction exhibits a competitive PCR activity (76.18 μmol g−1h−1 for CO production rate) increase of 31.6 and 20.3 times compared to TiO2 and CoAl-LDH, respectively.

Recent progress of MXene as a cocatalyst in photocatalytic carbon dioxide reduction

Due to the excessive consumption of fossil fuel resources and the emission of a substantial quantity of CO2 into the environment, it is urgent to develop clean energy solutions. In order to reduce carbon emissions from the source, it is effective approach to convert CO2 into various renewable energy fuels. Inspired by the photosynthesis of green plant, CO2 is converted into clean fuel with the aid of catalysts. Regarding the separation and transfer of photogenerated charge carriers, and inadequate adsorption and activation of CO2 on the surface of catalysts, the current semiconductors utilized in photocatalysis have low efficiency. As a result, the current efficiency of photocatalysts is far from meeting the need for practical industrial demands. MXene materials, for example Ti3C2Tx (9980 S cm−1), have emerged as a promising candidate for CO2 reduction due to the significant number of active sites for functional groups, high conductivity and low defects, large surface areas, and outstanding visible light photoelectronic properties. This review provides a critical overview of the recent progress regarding MXene as a co-catalyst in photocatalytic CO2 reduction systems. We systemically explore the fundamental principles and reaction mechanisms associated with separating and transferring photogenerated charge carriers. Additionally, we investigate the basic properties of MXene as a co-catalyst in the context of CO2 reduction. Furthermore, this review also elucidates the impacts of the microstructure of photocatalysts on enhancing photocatalytic performance. Finally, the challenges and opportunities in using MXene as a co-catalyst for CO2 reduction have been presented to inspire further research in this field.

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.

Defect and nanostructure engineering of polymeric carbon nitride for visible-light-driven CO2 reduction

Sunlight-induced photocatalytic carbon dioxide (CO2) reduction to energy-rich chemicals by metal-free polymeric carbon nitride (CN) semiconductor is a promising tactic for sustained solar fuel production. However, the reaction efficiency of CO2 photoreduction is restrained seriously by the rapid recombination of photogenerated carriers on CN polymer. Herein, we incorporate 2-aminopyridine molecule with strong electron-withdrawing group into the skeleton edge of CN layers through a facile one-pot thermal polymerization strategy using urea as the precursor, which renders a modified carbon nitride (ACN) with extended optical harvesting, abundant nitrogen defects and ultrathin nanosheet structure. Consequently, the ACN photocatalyst with desirable structural features attains enhanced separation and migration of photoexcited charge carriers. Under visible light irradiation with Co(bpy)32+ as a cocatalyst, the optimized ACN sample manifests a high CO2 deoxygnative reduction activity and high stability, providing a CO yielding rate of 17 μmol h−1, which is significantly higher than that of pristine CN. The key intermediates engaged in CO2 photoreduction reaction are determined by the in situ diffuse reflectance infrared Fourier transform spectroscopy, which sponsors the construction of the possible photocatalytic CO2 reduction mechanism on ACN nanosheets.