CO2 Photoreduction Performance Research Articles

One-pot Synthesis of Metal-coordinated Covalent Organic Frameworks for Enhanced CO2 Photoreduction.

Solar energy-driven reduction of CO2 into fuels with H2O as a sacrificial agent is a challenging but desirable subject in photosynthesis. Covalent organic frameworks (COFs) are considered promising candidates for this subject because of their designable structures and functions. The coordination of transition metal ions into COFs is a feasible way to boost the photocatalytic activity. However, postsynthetic modification of COFs with metal ions often leads to a significant decrease in crystallinity and the specific surface area. Herein, we develop a one-pot synthesis of metal-coordinated (nonnoble metal) COFs with high crystallinity. HB-TAPT + Co with ordered and segregated D-A arrays is synthesized by combining 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT, a strong electron-acceptor) with 2-hydroxy-1,3,5-benzenetricarbaldehyde (HB)-loaded Co2+ (a strong electron-donor). The CO production when using HB-TAPT + Co under visible light irradiation for 4 h is 78.4 μmol g-1, which is 3.2 times that of HB-TAPT + Co synthesized by the postsynthetic modification method and 2.65 times that of HB-TAPT without the metal ions. HB-TAPT + Co also has good recycling stability in photocatalytic CO2 reduction. Additionally, experimental results have demonstrated that the crystallinities of these metal-coordinated materials contribute greatly to the conversion of CO2 in the photoreaction with H2O. This work provides a new protocol for improving the CO2 photoreduction performance by coordinating metal ions to COFs while maintaining the original crystallinity through a one-pot synthesis method.

S-scheme CuWO4@g-C3N4 core-shell microsphere for CO2 photoreduction

Utilizing solar energy to achieve artificial photosynthesis of chemical fuel is prevalent in tackling CO2 excessive emissions and energy deficiency. Engineering tailored morphology and constructing matched heterostructure are two significant schemes to elevate the CO2 photoconversion efficiency of g–C3N4–based composite. Herein, a novel S-scheme CuWO4@g-C3N4 core-shell microspheres were designed by a template-free hydrothermal and annealing approach. The CuWO4@g-C3N4 composite exhibits improved visible light harvesting, increased BET specific area, and enhanced CO2 adsorption ability. Further, S-scheme CuWO4@g-C3N4 heterojunction facilitates charge separation and realizes strong redox capability, contributing to elevated CO2 photoreduction performance. The CO yield rate for CuWO4@g-C3N4 composite reaches about 4.15 μmol g−1 h−1, which is 2.7 folds that of bare g-C3N4 (1.56 μmol g−1 h−1). Theoretical calculations unveil that the hydrogenation and reduction of *OCHO to *HCOOH are involved in a higher Eb of 0.39 eV than CO (0.24 eV), contributing to a high selectivity for CO yield. This work can be employed to fabricate more various g–C3N4–based composites for artificial photosynthesis.

Interfacial Engineering of Semicoherent Interface at Purified CsPbBr3 Quantum Dots/2D-PbSe for Optimal CO2 Photoreduction Performance.

Heterogeneous photocatalysts are extensively used to achieve interfacial electric fields for acceleration of oriented charge carrier transport and further promotion of photocatalytic redox reactions. Unfortunately, the incoherent interfaces are almost present in the heterostructures owing to large lattice mismatch accompanied by the interfacial defects and high density of gap states, acting as high energy barriers for charge migration. In this work, we report the atomic engineering of CsPbBr3/PbSe heterogeneous interfaces and conversion from incoherent features to semicoherent characters via methyl acetate (MeOAc) purification of CsPbBr3 quantum dots (QDs) before composited with two-dimensional (2D)-PbSe, which is confirmed by high-resolution transmission electron microscopy. The photocatalytic performances and theoretical calculations indicate that semicoherent interfaces are favorable for improving the activity and reactivity of the heterostructure, triggering 3 times enhanced photocatalytic CO2 reduction rate with 91% selectivity and satisfactory stability. This study proposes a facile method for photocatalytic heterojunctions to transform incoherent interfaces to photocatalytically beneficial semicoherent boundaries, accompanying with a systematic analysis of the consequent chemical dynamics to demonstrate the mechanism of the semicoherent interface for supporting photocatalysis. The understandings gained from this work are valuable for rational interfacial lattice engineering of heterogeneous photocatalysts for efficient solar fuel production.

Modulating electronic structure of lattice O-modified orange polymeric carbon nitrogen to promote photocatalytic CO2 conversion

Adsorption and activation of CO2, and high carriers transform efficiency are of great significance for improving the CO2 photoreduction performance. However, electronic structure regulation plays an important role in the dynamical behavior of carriers. In this study, O atoms were successfully introduced into polymeric carbon nitrogen to synthesize an orange O-modified polymeric carbon nitrogen and achieve the rearrangement of electron density distribution, which promotes the adsorption and activation of CO2 and efficient separation and migration of carriers. DFT calculation demonstrates that the O atoms perform as the dominant active sites and reduce the free energy of determining step. Moreover, the introduction of O atoms broadens the light absorption range by changing the electronic layer structure of polymeric carbon nitrogen. Therefore, the fabricated O-modified polymeric carbon nitrogen exhibits significant performance. Under visible light irradiation, the CO generation efficiency achieved a 10-fold boost. We synthesize theory and experiment to highlight the important role of modulating electronic structure in designing photocatalysts.

0D-2D S-scheme CdS/WO3 catalyst for efficiently boosting CO2 photoreduction

Improving the dispersion of active sites and photogenerated carriers’ separation efficiency are of significant for enhancing the CO2 photoreduction. In this research, Zero-dimensional/Two-dimensional (0D-2D) S-scheme CdS/WO3 photocatalysts have been successfully obtained via the simple hydrothermal method and successive ionic layer adsorption reaction. SEM and TEM images provide that CdS Quantum Dots (QDs) are uniformly dispersed on the surface of WO3 nanosheets. WO3 nanosheets can greatly improve the dispersion of the CdS QDs, which can enlarge the adsorption and reaction efficiency of CO2 at the photoreduction sites. CO2 photoreduction tests show that the CdS/WO3 (CW-2) composite expresses excellent CO2 photoreduction ability and great catalytic stability. The yields of CO and CH4 with the CW-2 as catalyst are 64.7 μmol/g·h and 2.3 μmol/g·h, which are about 4.0 and 2.7 times more potent than that of CdS QDs. 13C calibration experiment proves that the C-source of CO and CH4 are obtained by the CO2 photoreduction process. Density functional theory calculation and electron spin resource results confirm the formation of S-scheme heterojunction. A potential synergistic effect of highly dispersed active sites and the S-scheme heterojunction has been provided for enhanced CO2 photoreduction performance.

Impact of transition metal incorporation on the photocatalytic CO2 reduction activity of polymeric carbon nitride

Incorporation of transition metals in polymeric carbon nitride (CN) is an effective strategy to enhance its photocatalytic CO2 reduction activity, however, the difference of activity enhancement by incorporating different metals is not well understood. Herein, CN is modified with different transition metals by pyrolyzing the mixtures of urea and metal-organic frameworks (MOFs) to obtain MCN (M = Cu, Co, Ti or Fe). For each given type of metal-modified CN, the photocatalytic CO2 reduction activity is optimized by controlling the content of MOF precursor during pyrolysis. The optimized MCN delivers significantly enhanced CO evolution rate than pure CN, in the order of CN (83 μmol g−1 h−1) < CuCN (246 μmol g−1 h−1) < CoCN (326 μmol g−1 h−1) < TiCN (454 μmol g−1 h−1) < FeCN (490 μmol g−1 h−1). It is revealed that for CuCN and CoCN, Cu and Co are doped in CN. In contrast, for TiCN and FeCN, Ti and Fe exist as TiO2 and Fe2O3 forming Z-scheme heterojunctions with CN. The progressively improved photocatalytic activity corresponds to the increased specific surface area, CO2 adsorption capacity, visible light absorption as well as charge separation and transfer efficiency. Furthermore, we design and prepare bimetal incorporated CN through combining metal doping with heterojunction construction strategies, i.e., Cu doped CN/TiO2 and Co doped CN/Fe2O3, which exhibit further enhanced CO2 photoreduction performance with CO evolution rates of 613 and 718 μmol g−1 h−1, respectively. This work provides insight into the design and preparation of highly efficient CN-based photocatalytic materials.

Multi-channel charge transfer of hierarchical TiO2 nanosheets encapsulated MIL-125(Ti) hollow nanodisks sensitized by ZnSe for efficient CO2 photoreduction

Metal-organic frameworks-based hybrids with desirable components, structures, and properties have been proven to be promising functional materials for photocatalysis and energy conversion applications. Herein, we proposed and prepared ZnSe sensitized hierarchical TiO2 nanosheets encapsulated MIL-125(Ti) hollow nanodisks with sandwich-like structure (MIL-125(Ti)@TiO2\\ZnSe HNDs) through a successive solvothermal and selenylation reaction route using the as-prepared MIL-125(Ti) nanodisks as precursor. In the ternary MIL-125(Ti)@TiO2\\ZnSe HNDs hybrid, TiO2 nanosheets were transformed from MIL-125(Ti) and in situ grown on both sides of the MIL-125(Ti) shell, forming sandwich-like hollow nanodisks, and the ratio of MIL-125(Ti)/TiO2 can be tuned by changing the solvothermal time. The ternary hybrids possess the advantages of enhanced incident light utilization and abundant accessible active sites originating from bimodal pore-size distribution and hollow sandwich-like heterostructure, which can effectively promote CO2 photoreduction reaction. Especially, the formed multi-channel charge transfer routes in the ternary heterojunctions contribute to the charge transfer/separation and extend the lifespan of charge-separated state, thus boosting CO2 photoreduction performance. The CO (513.1 μmol g−1h−1) and CH4 (45.1 μmol g−1h−1) evolution rates over the optimized ternary hybrid were greatly enhanced compared with the single-component and binary hybrid photocatalysts.

Cu Nanoparticles Modified Step-Scheme Cu2O/WO3 Heterojunction Nanoflakes for Visible-Light-Driven Conversion of CO2 to CH4.

In this study, Cu and Cu2O hybrid nanoparticles were synthesized onto the WO3 nanoflake film using a one-step electrodeposition method. The critical advance is the use of a heterojunction consisting of WO3 flakes and Cu2O as an innovative stack design, thereby achieving excellent performance for CO2 photoreduction with water vapor under visible light irradiation. Notably, with the modified Cu nanoparticles, the selectivity of CH4 increased from nearly 0% to 96.7%, while that of CO fell down from 94.5% to 0%. The yields of CH4, H2 and O2 reached 2.43, 0.32 and 3.45 mmol/gcat after 24 h of visible light irradiation, respectively. The boosted photocatalytic performance primarily originated from effective charge-transfer in the heterojunction and acceleration of electron-proton transfer in the presence of Cu nanoparticles. The S-scheme charge transfer mode was further proposed by the in situ-XPS measurement. In this regard, the heterojunction construction showed great significance in the design of efficient catalysts for CO2 photoreduction application.

Z-type heterojunction of Cu2O-modified layered BiOI composites with superior photocatalytic performance for CO2 reduction

For solar energy conversion and energy mitigation relief, the development of an efficient and stable photocatalyst is critical. A Z-type Cu2O-modified BiOI microspheres were synthesized by chemical deposition. A series of xCu2O/BiOI (x = 0.6, 0.8, 1.0) has improved CO2 photoreduction performance under simulated sunshine irradiation, and the best yields of CH3OH and C2H5OH were 609.05 and 273.96 μmol/gcat, respectively, which were 2.65 and 2.88 times larger than that of pure BiOI. The material exhibits strong photocatalytic performance, which is mainly owing to a greater interaction between Cu2O and BiOI, which promotes the separation and migration of photogenerated carriers as well as the use of sunlight. The specific surface areas of pure BiOI and 10% Cu2O/BiOI were 12.05 and 22.85 m2/g, respectively, as shown in the N2 adsorption-desorption characterization, indicating that the introduction of Cu2O increased the specific surface area of BiOI and provided more active sites. Various characterizations were carried out to evaluate the morphological structure of the Z-type composite of Cu2O/BiOI composite catalyst and to investigate a possible mechanism of CO2 reduction. The CO2 reduction performance of the composite catalyst did not decrease significantly through five cycles of testing, indicating that the material has good stability and redox performance. This research suggests that photocatalysts could be useful in solar energy conversion and energy crisis mitigation.

Synergistic effect stemming from vertically anchored seamless 2D MoSe2 nanosheets on 1D NiTiO3 nanofibers toward CO2 photoreduction

Herein, nickel titanate nanofiber/molybdenum diselenide nanosheet (NiTiO3 NF/MoSe2) heterostructures were prepared and their photocatalytic CO2 photoreduction performance was assessed. The heterostructures were synthesized via a facile two-step synthesis route combining an electrospinning technique followed by a solvothermal method. The MoSe2 nanosheets were vertically anchored to the surface of NiTiO3 NF, thereby increasing the number of exposed active edges that are pivotal to photocatalytic performance. By tuning the loading of MoSe2 in the heterostructure, the optimal condition was obtained for the fabrication of the NiTiO3 NF/MoSe2 heterojunctions. The as-prepared heterojunctions exhibited higher photocatalytic activity than pure NiTiO3 NF and MoSe2 for the photocatalytic reduction of CO2 under ultraviolet-visible light irradiation. Among the several hybrid samples, the optimal sample displayed a 6.6- and 7.7-fold enhanced production of CO (386 µmol g–1) compared with that of pure NiTiO3 NF (58 µmol g–1) and pure MoSe2 (50 µmol g–1), respectively, with overall CO2 selectivity of 86%. This enhanced photocatalytic activity was attributed to synergy created by tailored loading of MoSe2 nanosheets onto the 1D NiTiO3 NF. This hierarchical growth of MoSe2 over NiTiO3 NF provided more exposed edge sites, enhanced light absorption over the entire spectrum, and improved separation of photogenerated electrons and holes at the NiTiO3 NF/MoSe2 heterojunction interface. Such NiTiO3 NF/MoSe2 heterojunctions with broad spectral photocatalytic performance have potential applications in water splitting and water treatment.

Boosted CO2 photoreduction performance on Ru-Ti3CN MXene-TiO2 photocatalyst synthesized by non-HF Lewis acidic etching method

Photocatalytic CO2 reduction to produce value-added products is considered a promising solution to solve the global energy crisis and the greenhouse effect. In this study, Ti3CN MXene was synthesized using a Lewis acidic etching method without the usage of toxic hydrofluoric acid (HF). Ti3CN MXene was then used as a support for the in situ hydrothermal growth of TiO2 and Ru nanoparticles. In the presence of 0.5 wt% Ru, Ru-Ti3CN-TiO2 shows CO and CH4 production rates of 99.58 and 8.97 μmol/g, respectively, in 5 h under Xenon lamp irradiation, more than 20.5 and 9.3 times that of commercial P25. The enhancement in photocatalytic activity was attributed to the synergy between the in-situ growth of TiO2 on Ti3CN MXene and Ru nanoparticles. It was proven experimentally that Ti3CN MXene can provide abundant pathways for electron transfer. The separation and transfer of the photo-induced charge were further increased with the help of Ru and Ti3CN MXene, leaving more electrons to participate in the subsequent CO2 reduction reaction. We believe that this work will encourage more attention to designing environment-friendly MXene-based photocatalysts for CO2 photoreduction using the non-HF method.

Steering Unit Cell Dipole and Internal Electric Field by Highly Dispersed Er atoms Embedded into NiO for Efficient CO2 Photoreduction

AbstractThe weak internal electric field over antiferromagnetic materials makes it difficult to facilitate charge migration to the surface, leading to low performance for CO2 photoreduction. The asymmetry and polarization refinement structure can induce an intensive internal electric field. Herein, n‐type NiO is synthesized with highly dispersed erbium atoms doping (Er/NiO1−x) via a molten salt method to accelerate charge separation and transfer. The doping of Er atoms can distort the unit cell of NiO to alter the symmetry and enhance the polarization and internal electric field, in favor of efficient separation of charges. In addition, the highly dispersed erbium‐doped n‐type NiO can largely boost the adsorption and activation of CO2, and weaken the energy barrier for CO2 photoreduction reaction. Benefiting from the unique features, an optimal doping ratio (≈2%) with erbium atoms achieves a remarkable elevation in carrier separation efficiency and excellent CO2 photoreduction performance with a CO yield of 368 µmol g−1 h−1 in the Ru(byp)32+/ethanolamine electron‐agent generating system, which is 26.3‐fold and 3.9‐fold relative to traditional NiO and n‐type NiO, respectively. The obtained Er/NiO1−x photocatalyst and the unit cell dipole governing the internal electric field opens a new window for CO2 photoreduction in antiferromagnetic materials.

Efficient charge transfer and CO2 photoreduction of hierarchical CeO2@SnS2 heterostructured hollow spheres with spatially separated active sites

Heterostructured hybrids with hollow configuration and efficient charge separation are very promising for CO2 photoreduction. This study demonstrates the design and fabrication of hierarchical double-shelled CeO2@SnS2 hollow spheres with spatially separated active sites (MnOx/CeO2@SnS2/Ni2P DSHSs) for efficient CO2 photoreduction. In this catalyst system, MnOx and Ni2P cocatalysts are selectively anchored on the CeO2 and SnS2 shells, respectively, forming spatially separated active sites. The confinement effect of outer-surface SnS2 nanosheets offers more opportunities for Ni2P cocatalyst to react with CO2 molecules. Owing to the desired hierarchical double-shelled hollow architecture and spatially-separated cocatalysts, the MnOx/CeO2@SnS2/Ni2P DSHSs possess the advantages of abundant spatially-separated active sites, enhanced visible-light harvesting, and accelerated charge separation. As expected, the optimized MnOx/CeO2@SnS2/Ni2P DSHSs sample exhibits remarkable CO2 photoreduction activity. The CO yield and selectivity reach 29.67 μmol g−1 h−1 and 90.1%, respectively, which are remarkably higher than the control samples. This study demonstrates a promising strategy to construct well-defined hierarchical hybrid catalysts for maximizing CO2 photoreduction performance.

“Electron collector” Bi19S27Br3 nanorod-enclosed BiOBr nanosheet for efficient CO2 photoconversion

Although CO2 photoreduction is a promising method for solar-to-fuel conversion, it suffers from low charge transfer efficiency of the photocatalysts. To improve the CO2 photoreduction performance, introduction of electron-accumulated materials on the photocatalyst surface is considered an effective method. In this study, the Bi19S27Br3/BiOBr composites were designed and synthesized. The Bi19S27Br3 nanorod in this photocatalytic system acts as an electron-accumulated active site for extracting the photogenerated electrons on the BiOBr surface and for effectively activating the CO2 molecules. As a result, Bi19S27Br3/BiOBr composites exhibit the higher charge carrier transfer efficiency and further improves the CO2 photoreduction performance relative to that of pure Bi19S27Br3 and BiOBr. The rate of CO formation using Bi19S27Br3/BiOBr-5 is about 8.74 and 2.40 times that using Bi19S27Br3 and BiOBr, respectively. This work provides new insights for the application of Bi19S27Br3 as an electron-accumulating site for achieving high photocatalytic CO2 reduction performance in the future.

Engineering unsaturated coordination of conductive TiOx clusters derived from Metal–Organic–Framework incorporated into hollow semiconductor for highly selective CO2 photoreduction

Solar-driven CO2 conversion into fuels is a promising solution toward green energy conversion. It is a challenge to regulate the precise structure of photocatalysts at the atomic scale, facilitating the charge transfer and improving CO2 photoreduction performance. Herein, conductive Ti3+-rich TiOx clusters with unsaturated Ti–O5 coordination incorporated into nanosheets-assembled hollow sulfide semiconductors were prepared through a versatile transformation strategy by using NH2-MIL-125(Ti) metal–organic–framework as precursor. This typical photocatalysts exhibit highly selective photoreduction of CO2, achieving a super high visible-light photocatalytic CO evolution activity of 1100 μmol g−1h−1. The active sites were identified on the surface of conductive TiOx clusters, inducing efficient trapping of photogenerated electrons at the interface and suppressing H2 generation. This enhanced performance is ascribed to Ti3+-rich TiOx clusters as an efficient cocatalyst on sulfide semiconductor providing more active sites due to electrical conductivity and unsaturated coordination environment. This work provides a promising approach to enhance photocatalytic performance of the catalysts coupled by unique metal oxide clusters for selective photoreduction of CO2.

Electron-coupled enhanced interfacial interaction of Ce-MOF/Bi2MoO6 heterostructure for boosted photoreduction CO2

To achieve the task of “Carbon neutrality” in China, the photoreduction of CO2 was applied over the solid-phase synthesized Ce-MOF/Bi2MoO6 heterostructure. The inexhaustible driven force of sunlight was adopted and the value-added chemicals of methane, methanol and formic acid were obtained during photoreduction. The firstly successful construction of Ce-MOF/Bi2MoO6 heterostructure was generated by their intense contact via the electron-coupled structure, which could take full advantage of the high surface area of Ce-MOF and the efficient electrons transfer of Bi2MoO6. The segregation and transport of photoexcited carriers were heightened by the enhanced interfacial interaction. Moreover, the generation of HCOOH appeared only over the composites, which was caused by the inhibition of the fast interaction between the photoexcited electrons and CO2-reduced intermediates. As a result, the CO2 photoreduction performance of electrons-induced heterostructured of Ce-MOF/Bi2MoO6 composites exhibited higher CH4, CH3OH and HCOOH yield amount than the neat Ce-MOF and BMO. The optimized photocatalyst reached up to 113.87 μmol·h−1·g−1 of CH4, 40.59 μmol·h−1·g−1 of CH3OH and 73.48 μmol·h−1·g−1 of HCOOH. The mechanism of CO2 photoreduction process was gained by ESR and in-situ DRIFTS techniques.

Frustrated Lewis Pair Sites Boosting CO2 Photoreduction on Cs2CuBr4 Perovskite Quantum Dots

Lead (Pb) halide perovskite quantum dots (PQDs) are promising candidates for the photochemical reduction of CO2. However, the intrinsically weak adsorption and activation toward inert CO2 molecules have seriously hindered their practical application. This study reports alternative Cs2CuBr4 PQDs for gas–solid phase photocatalytic CO2 reduction under simulated solar irradiation. Cs2CuBr4 PQDs exhibited CO2 photoreduction performance with CH4 and CO yields of 74.81 and 148.98 μmol g–1, respectively. In situ diffuse reflectance infrared Fourier transform spectra and density functional theory calculations cooperatively revealed the synergistic strengthening of microelectronic polarization in Cs2CuBr4 PQDs induced by surface-frustrated Lewis pair-like properties and intrinsic Cu d-band properties facilitated robust CO2 adsorption and activation. This study demonstrated the potential of Cs2CuBr4 PQDs as a platform for highly efficient CO2 photoreduction and provided a distinct concept for CO2 adsorption and activation based on the catalytic mechanism of Cu-based PQDs.

Constructing hierarchical ZnIn2S4/g-C3N4 S-scheme heterojunction for boosted CO2 photoreduction performance

Tubular graphitic carbon nitride (g-C3N4) photocatalyst has received considerable attention in solar to chemical energy conversion due to its appealing intrinsic photoelectrical properties and the favorable geometric configuration. However, it still suffers from severe charge recombination, which causes moderate photocatalytic performance. Herein, ZnIn2S4 nanosheets modified hexagonal g-C3N4 tubes (ZIS/HCNT) were fabricated through an in situ growth approach. By rational construction of large contact area and strong interfacial interaction, an effective Step like-scheme (S-scheme) charge transfer mode was established over ZIS/HCNT, which was confirmed by the in situ X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) analysis. Benefited from the facilitated charge separation efficiency and remained strong redox abilities, ZIS/HCNT exhibited significantly improved photocatalytic conversion rate of CO2 to CO (883 μmol h−1 g−1), which was about 13 and 2.4 times higher than that of HCNT and ZIS, respectively. This work provides a paradigm of upgrading photocatalytic CO2 reduction through a rational structural design to regulate charge transfer.

A distinctive semiconductor-metalloid heterojunction: unique electronic structure and enhanced CO2 photoreduction activity

Increasing the concentration and separation ability of charge carriers in photocatalysts has still been a crucial issue and challenge to achieve high CO2 photoreduction performance. Here, we construct a distinctive heterojunction between semiconductor (CeO2) and metalloid (CuS). It has been discovered that, different from conventional semiconductor and Schottky heterojunctions, in this system, electrons (esc-) located at the conduction band (CB) of CeO2 will transfer to the Fermi level in partially occupied band (CB) of CuS and accumulate there. Then, together with transition electrons (etr-) excited from the CB below Fermi level or fully filled band (B-1) of CuS, these esc- will further transfer to the lowest unoccupied band (B1) of CuS, finally participate in CO2 reduction reaction. Because the concentration and separation efficiency of charge carriers has been obviously increased, this heterojunction exhibits remarkably enhanced CO2 photoreduction performance. In-situ FTIR was conducted to explore the reaction process and the changes of intermediates on the surface of this catalyst during CO2 photoreduction. Given that this type of heterojunction can only be established between a semiconductor and a metalloid and exhibits special electron transfer behavior, this work really provides an unconventional strategy for the design of photocatalysts with superior CO2 photoreduction activity.

Efficient charge transfer in cadmium sulfide quantum dot-decorated hierarchical zinc sulfide-coated tin disulfide cages for carbon dioxide photoreduction

Constructing hybrid photocatalysts with advanced structures and controllable compositions is a promising way to improve CO2 photoreduction performance. In this work, SnS2 nanosheets are grown on ZnS polyhedron cages to fabricate hierarchical ZnS@SnS2 double-shelled heterostructured cages. This design integrates ZnS cages and SnS2 nanosheets into a stable heterostructured hybrid catalyst with a hierarchical double-shelled cage-like architecture, possessing abundant active sites, quick charge separation/migration, and high CO2 adsorption capacity. Benefiting from these advantages, the optimized hierarchical ZnS@SnS2 heterostructured cages exhibit significant gas-phase CO2 photoreduction activity with a CO generation rate of 95.38 μmol g−1h−1 and 72.4% CO selectivity, which are greatly improved in comparison with those of pure ZnS cages and nanosheet-assembled SnS2 particles. Furthermore, charge carrier separation efficiency and visible light harvesting ability are further improved by constructing a ZnS@SnS2/CdS type-I/type-II complex heterostructured system through surface decoration of CdS quantum dots. The optimized ZnS@SnS2/CdS hybrid exhibits a CO generation rate of 155.57 μmol g−1h−1 and an excellent selectivity of 80.4%. This work is conducive to the design and manufacture of advanced hybrids for solar energy utilization and photocatalytic reactions.