Photocatalytic CO2 Research Articles

Cobalt Phthalocyanine-Based Covalent Organic Framework with Bimetallic Synergistic Effect for Efficient Photocatalytic CO2 Reduction

Cobalt Phthalocyanine-Based Covalent Organic Framework with Bimetallic Synergistic Effect for Efficient Photocatalytic CO₂ Reduction

The Reduced Barrier for the Photogenerated Charge Migration on Covalent Triazine‐Based Frameworks for Boosting Photocatalytic CO2 Reduction Into Syngas

AbstractPhotocatalytic CO2 reduction together with hydrogen generation is a promising approach to generate syngas, the photogenerated electron migration from photosensitizers to the catalytic active sites is the rate‐determining step. Herein, an integrative strategy is presented by covalently grafting metal complexes into donor–acceptor covalent triazine‐based frameworks. The catalytic active sites are integrated with the photosensitizer units by covalent linkages to form an extended π‐conjugated framework, which significantly reduces the energy barrier for the migration of the photogenerated charge carriers, resulting in high activity and durability in photocatalytic CO2 reduction into syngas under visible light irradiation. The CO and H2 evolution amounts in 1.5 h are 1086 and 1042 µmol g−1, respectively, which greatly surpass those in the host‐guest counterparts. Furthermore, selective adsorption for CO2 over N2 renders this photocatalytic system to be effective for syngas production from the simulated flue gas. This study provides new approaches to construct the integrative photocatalytic systems for solar‐to‐chemical energy conversion.

Alkalized MQDs/Bi2S3 Porous Structure for Efficient Photocatalytic CO2 Reduction

AbstractFinding effective and specific catalytic materials for the transformation of carbon dioxide into fuel is indisputably a significant challenge. In this study, 3D porous sphere structure MXene quantum dot/Bi2S3 (MBS) composites were prepared using electrostatic self‐assemblage of protonated Bismuth sulphide nanoparticles (Bi2S3 NSs) with Ti3C2(OH)2 QDs (MQDs‐OH). The optimized MBS material demonstrates an excellent narrow band gap (Eg=1.24 V (vs. NHE)) and high selectivity and efficiency in catalyzing CH3OH, delivering impressive yields of up to 694.7 μmol/g. This study may lead to a new approach to the development of multidimensional photocatalysts for CH3OH production by adsorption of atmospheric CO2.

Covalent Organic Framework Stabilized Single CoN4Cl2 Site Boosts Photocatalytic CO2 Reduction into Tunable Syngas

AbstractSolar carbon dioxide (CO2) reduction provides an attractive alternative to producing sustainable chemicals and fuel. However, the construction of a highly active photocatalyst was challenging because of the rapid charge recombination and sluggish surface CO2 reduction. Herein, a unique Co−N4Cl2 single site was fabricated by loading Co species into the 2,2′‐bipyridine and triazine‐containing covalent organic framework (COF) for CO2 conversion into syngas under visible light irradiation. The resulting champion catalyst TPy‐COF‐Co enabled a record‐high CO production rate of 426 mmol g−1 h−1, associated with the unprecedented turnover number (TON) and turnover frequency (TOF) of 2095 and 1607 h−1, respectively. The catalyst also exhibited favorable recycling performance and widely adjustable syngas production (CO/H2 ratio: 1.8 : 1–1 : 16). A systematical investigation including operando synchrotron X‐ray absorption fine structure (XAFS) spectroscopy, in situ attenuated total reflection surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRAS), and theoretical calculation indicated that the triazine‐based COF framework promoted the charge transfer towards the single Co−N4Cl2 sites that greatly promoted the CO2 activation by lowering the energy barrier of *COOH generation, facilitating the CO2 transformation. This work highlights the great potential of the molecular regulation of COF‐derived single‐atom catalysts to boost CO2 photoreduction efficiency.

An Electron Bridge of Shared Atoms Mediated Cs3Bi2Br9/Bi2WO6 Z‐Scheme Heterojunction for Photocatalytic CO2 Reduction

AbstractConverting clean solar energy into chemical energy through artificial photosynthesis is an effective solution to solve the energy and environmental issues. Here, we report a Cs3Bi2Br9/Bi2WO6 (CBB/BWO) Z‐scheme heterojunction constructed via electrostatic self‐assembly, which facilitates efficient separation of photogenerated carriers and ensures the corresponding redox capacity of both components. By sharing Bi atoms, a Br−Bi−O bond is established between CBB and BWO, serving as an “electron bridge”. The electrons generated by BWO are efficiently channeled to CBB through the heterojunction‐formed “electron bridge”, thereby achieving effective photocatalytic CO2 reduction. Under simulated sunlight conditions, it exhibits the highest CO yield of 72.52 μmol g−1 (without the addition of any precious metal, photosensitizers or sacrifices), which is approximately 7‐fold and 18‐fold greater than that of pure CBB and BWO, respectively. This work provides a more profound comprehension of the regulation of electron transfer through interfacial chemical bonds, thereby proposing a promising strategy for the development of efficient heterojunction photocatalysts for CO2 photoreduction.

Integration of Plasmonic Ag(I) Clusters and Fe(II) Porphyrinates into Metal–Organic Frameworks for Efficient Photocatalytic CO2 Reduction Coupling with Photosynthesis of Pure H2O2

AbstractEfficient photocatalytic CO2 reduction coupled with the photosynthesis of pure H2O2 is a challenging and significant task. Herein, using classical CO2 photoreduction site iron porphyrinate as the linker, Ag(I) clusters were spatially separated and evenly distributed within a new metal–organic framework (MOF), namely Ag27TPyP‐Fe. With water as electron donors, Ag27TPyP‐Fe exhibited remarkable performances in artificial photosynthetic overall reaction with CO yield of 36.5 μmol g−1 h−1 and ca. 100 % selectivity, as well as H2O2 evolution rate of 35.9 μmol g−1 h−1. Since H2O2 in the liquid phase can be more readily separated from the gaseous products of CO2 photoreduction, high‐purity H2O2 with a concentration up to 0.1 mM was obtained. Confirmed by theoretical calculations and the established energy level diagram, the reductive iron(II) porphyrinates and oxidative Ag(I) clusters within an integrated framework functioned synergistically to achieve artificial photosynthesis. Furthermore, photoluminescence spectroscopy and photoelectrochemical measurements revealed that the robust connection of Ag(I) clusters and iron porphyrinate ligands facilitated efficient charge separation and rapid electron transfer, thereby enhancing the photocatalytic activity.

Active Site Engineering in Reticular Covalent Organic Frameworks for Photocatalytic CO2 Reduction (Adv. Funct. Mater. 43/2024)

Active Site Engineering in Reticular Covalent Organic Frameworks for Photocatalytic CO₂ Reduction (Adv. Funct. Mater. 43/2024)

Enhanced Water Dissociation Promotes Photocatalytic CO2 Hydrogenation to Methane: A Case Study of Pt-Loaded MoO3 Catalyst

Enhanced Water Dissociation Promotes Photocatalytic CO₂ Hydrogenation to Methane: A Case Study of Pt-Loaded MoO₃ Catalyst

Self‐Confined Construction of Facet Heterojunction with Tunable Band Alignment for Enhanced Photocatalytic CO2 Reduction

AbstractAlthough crystal facet engineering is extensively studied in energy and environmental technologies, the in‐depth understanding of intrinsic mechanisms governing crystal facet heterojunctions in tuning band alignments is still limited. Here, novel Bi5O7NO3 crystals exposing tailor {080} facets are synthesized via NH4+‐assisted self‐confined construction. It has been confirmed that NH4+ ions selectively adsorb on the {141} facets, inversely inducing the growth of desired {080} crystal facets, while the tailored {080} facets facilitate the generation of oxygen vacancies. The controllable concentration of oxygen vacancies, influenced by different exposed facets, can optimize the relative positions of Fermi levels and shift the photoelectron transfer route between the {141} and {080}‐OV facets from type‐II to S‐scheme, thus triggering rapid charge transport channels and effectively suppressing electron‐hole recombination. DFT calculation verifies that the energy barrier for the *COOH formation on Bi5O7NO3‐{080}‐OV is the lowest, thereby promoting the generation of CO. The well‐designed Bi5O7NO3 crystals with the optimal {080}/{141} facet ratio exhibit a 3.8‐fold enhancement in photocatalytic CO2 reduction, compared to traditional Bi5O7NO3 dominated by the {141} facets. This work offers new insights into the regulation of band alignments at heterointerfaces and the design of high‐efficiency photocatalysts.

Synergistic Engineering of Electron‐Enriched Nickel Sites for Highly Efficient Photocatalytic CO2 Reduction to C2H6

Synergistic Engineering of Electron‐Enriched Nickel Sites for Highly Efficient Photocatalytic CO₂ Reduction to C₂H₆

Optimizing Reaction Kinetics and Thermodynamics for Photocatalytic CO2 Reduction through Spin Polarization Manipulation

Optimizing Reaction Kinetics and Thermodynamics for Photocatalytic CO₂ Reduction through Spin Polarization Manipulation

Inside Cover: Photocatalytic CO2 Reduction by Near‐Infrared‐Light (1200 nm) Irradiation and a Ruthenium‐Intercalated NiAl‐Layered Double Hydroxide (Angew. Chem. Int. Ed. 45/2024)

Inside Cover: Photocatalytic CO₂ Reduction by Near‐Infrared‐Light (1200 nm) Irradiation and a Ruthenium‐Intercalated NiAl‐Layered Double Hydroxide (Angew. Chem. Int. Ed. 45/2024)

Surface-Integrating Oxygen Vacancy and CuxO Nanodots Enabling Synergistic Electric Field and Dual Catalytic Sites Boosting CO2 Photoreduction.

High carrier separation efficiency and rapid surface catalytic reaction are crucial for enhancing catalytic CO2 photoreduction reaction. Herein, integrated surface decoration strategy with oxygen vacancies (Ov) and anchoring CuxO (1 < x < 2) nanodots below 10nm is realized on Bi2MoO6 for promoting CO2 photoreduction performance. The charge interaction between Ov and anchored CuxO enables the formation of enhanced internal electric field, which provides a strong driving force for accelerating the separation of photocharge carriers on the surface of Bi2MoO6 (ηsurf ≈71%). They can also cooperatively reduce the surface work function of Bi2MoO6, facilitating the migration of carrier to the surface. Meanwhile, surface-integrated Ov and CuxO nanodots allowing dual catalytic sites strengthens the adsorption and activation CO2 into *CO2 over Bi2MoO6, considerably boosting the progression of CO2 conversion process. In the absence of co-catalyst or sacrificial agent, Bi2MoO6 with Ov and CuxO nanodots achieves a photocatalytic CO generation rate of 12.75µmol g-1 h-1, a remarkable increase of over ≈15 times that of the original counterpart. This work provides a new idea for governing charge movement behaviors and catalytic reaction thermodynamics on the basis of synergistic improvement of electric field and active sites by coupling of the internal defects and external species.

Construction of BiVO4@ NiCo2O3 Heterojunction to Promote Photocatalytic CO2 Reduction

AbstractConstructing a catalyst capable of reducing CO2 through photoreduction in aqueous environments presents a significant challenge. In this study, we present the synthesis of BiVO4@NiCo2O3 heterojunction using a straightforward hydrothermal method for CO2 photoreduction. The sample with the optimal loading ratio demonstrates a CO generation rate of 7.202 μmol ⋅ g−1 ⋅ h−1, which is twice that of pure BiVO4 (3.626 μmol ⋅ g−1 ⋅ h−1) and 1.5 times that of pure NiCo2O3 (4.726 μmol ⋅ g−1 ⋅ h−1). Analysis using XPS and EPR techniques suggests that electron transfer at the interface of the heterojunction facilitates the separation of photogenerated charge carriers, thereby enhancing the efficiency of the photocatalytic process. This investigation offers a viable approach for developing photocatalysts for CO2 reduction in aqueous environments.

Synergistic N-heterocyclic carbene and C2N integration for efficient and selective metal-free photocatalytic CO reduction to C2H5OH

In the pursuit of sustainable and highly efficient catalysts for the reduction of CO to valuable multi-carbon fuels, this study presents a novel metal-free catalyst, C/C2N, created by integrating N-heterocyclic carbene (NHC) into a C2N monolayer. Utilizing density functional theory, we demonstrate that this integration effectively addresses the individual limitations of C2N and NHC, neither of which can stably adsorb CO molecules on their own. The synergistic effect of C2N and NHC facilitates distinct CO adsorption energies on the C2N surface (−0.08 eV) and at the NHC site (−0.83 eV), leading to an exceptionally low C–C coupling energy barrier of 0.41 eV, surpassing traditional metal-based catalysts. Computational results reveal that C/C2N exhibits outstanding activity and selectivity in reducing CO to C2H5OH, with a remarkably low free energy barrier of only 0.34 eV, further reducible to 0.20 eV under alkaline conditions. Furthermore, the integration of NHC into the C2N monolayer markedly narrows its band gap, enhancing visible light absorption and optimizing band edge positions, suggesting its potential for visible-light-driven reactions. Our findings establish C/C2N as an effective and selective metal-free photocatalyst with a notably low C–C coupling energy barrier, offering a novel avenue for CO conversion to multi-carbon fuels.

Computational Investigation on Cr-Doped Sc2CO2 MXene under Strain for Electronic Properties, Quantum Capacitance, and Photocatalytic Activity.

Sc2CO2 MXene has potential applications in energy storage and optoelectronics due to its superior structure and excellent properties. The electronic properties, quantum capacitance, and photocatalytic activity of Cr-doped Sc2CO2 under strain are studied by the density functional theory. Cr doping makes the system produce magnetism. The spin-down states of Sc2CO2-Cr under strain are direct semiconductors, while their spin-up states are indirect semiconductors. Sc2CO2-Cr under +5, -5, -3, and -2% strains in an aqueous system are suitable for cathode material. A large voltage drastically modulates the type of electrode materials. Sc2CO2-Cr under strains from 0 to +2% can perform the oxygen evolution reaction at an alkaline environment, while the Sc2CO2-Cr system under strain is a good for CO2 photocatalysis at pH 0 and 7.

Remarkable CO2 photocatalytic reduction enabled by UiO-66-NH2 anchored on flower-like ZnIn2S4

The utilization of renewable solar energy for the photocatalytic transformation of carbon dioxide (CO2) into valuable chemical substances is considered an optimal strategy to simultaneously address climate challenges and tackle energy scarcity. Herein, we prepared heterojunction photocatalysts UiO-66-NH2/ZnIn2S4, which were successfully applied in the photocatalytic reduction of CO2. The yield of the main product CO, for the optimal UiO-66-NH2/ZnIn2S4-2 sample could reach up to 57 μmol g−1h−1 when converting CO2 under the visible light irradiation, which was approximately 3.35 and 2.71 times higher than that achieved by the individual UiO-66-NH2 and ZnIn2S4 samples, respectively. The better photocatalytic performance of the UiO-66-NH2/ZnIn2S4-2 composites can be attributed to its synergistic effect resulting from tight interfacial contacts, special charge transfer pathways and excellent CO2 adsorption capacity. Furthermore, the intimate contact between UiO-66-NH2 and flower-like ZnIn2S4 accelerates electron transmission while effectively suppressing the quenching of photogenerated carriers. This research provides vital knowledge for the rational design of heterostructures aimed at enhancing the efficiency of CO2 photocatalysis for solar fuel production.

Photocatalytic CO2 Reduction by Near‐Infrared‐Light (1200 nm) Irradiation and a Ruthenium‐Intercalated NiAl‐Layered Double Hydroxide

AbstractNear‐infrared light‐driven photocatalytic CO2 reduction (NIR‐CO2PR) holds tremendous promise for the production of valuable commodity chemicals and fuels. However, designing photocatalysts capable of reducing CO2 with low energy NIR photons remains challenging. Herein, a novel NIR‐driven photocatalyst comprising an anionic Ru complex intercalated between NiAl‐layered double hydroxide nanosheets (NiAl‐Ru‐LDH) is shown to deliver efficient CO2 photoreduction (0.887 μmol h−1) with CO selectivity of 84.81 % under 1200 nm illumination and excellent stability over 50 testing cycles. This remarkable performance results from the intercalated Ru complex lowering the LDH band gap (0.98 eV) via a compression‐related charge redistribution phenomenon. Furthermore, transient absorption spectroscopy data verified light‐induced electron transfer from the Ru complex towards the LDH sheets, increasing the availability of electrons to drive CO2PR. The presence of hydroxyl defects in the LDH sheets promotes the adsorption of CO2 molecules and lowers the energy barriers for NIR‐CO2PR to CO. To our knowledge, this is one of the first reports of NIR‐CO2PR at wavelengths up to 1200 nm in LDH‐based photocatalyst systems.

Upgrading Single S-Scheme Heterojunction to Multi-S-Scheme Ones for Better Synergy of Photocatalytic CO2 Reduction and H2O Oxidation: The Third Component Location Matters

Upgrading Single S-Scheme Heterojunction to Multi-S-Scheme Ones for Better Synergy of Photocatalytic CO₂ Reduction and H₂O Oxidation: The Third Component Location Matters

Molten Salt Synthesis of Ti3C2/Cu Cocatalyst for Enhanced TiO2 Photocatalytic CO2 Reduction

AbstractPhotocatalytic reduction of CO2 is considered as a crucial pathway towards achieving sustainable energy and environmental goals. Nonetheless, attaining efficient CO2 conversion poses significant challenges, primarily due to the slow dynamics of charge carriers and the high activation energy required to break C=O bonds. In this study, a novel strategy involving Lewis acid molten salt etching is investigated to engineer a titanium oxide (TiO2)‐based photocatalysts with dual electron transfer channels (i. e., Ti3C2/Cu), which targets the photoreduction of CO2 to CO and CH4. Thanks to the dual electron transfer channels presented in the cocatalysts (Ti3C2/Cu), in conjunction with the numerous heterogeneous interfaces between TiO2 and the Ti3C2/Cu cocatalysts, this hybrid catalyst not only reduces charge transfer resistance but also accelerates the dynamics of photogenerated charge carriers. Consequently, the TiO2/Ti3C2/Cu hybrid catalyst demonstrates an exceptional photocatalytic CO2 reduction rate of 13.67 μmol g−1 h−1, with a total utilized photoelectron number (UPN) of 102.34 μmol g−1 h−1. which is 3.99‐fold higher than that of unmodified TiO2. This research provides a new approach for the preparation of dual cocatalysts through a one‐step molten salt synthesis process.