Selective Photocatalytic CO2 Reduction Research Articles

A Bifunctional Catalyst Derived from Copper Metal−Organic Framework for Highly Selective Photocatalytic CO2 Reduction and CO2 Cycloaddition Reaction

A Bifunctional Catalyst Derived from Copper Metal−Organic Framework for Highly Selective Photocatalytic CO2 Reduction and CO2 Cycloaddition Reaction

Asymmetric Cu(I)─W Dual-Atomic Sites Enable C─C Coupling for Selective Photocatalytic CO2 Reduction to C2H4.

Solar-driven CO2 reduction into value-added C2+ chemical fuels, such as C2H4, is promising in meeting the carbon-neutral future, yet the performance is usually hindered by the high energy barrier of the C─C coupling process. Here, an efficient and stabilized Cu(I) single atoms-modified W18O49 nanowires (Cu1/W18O49) photocatalyst with asymmetric Cu─W dual sites is reported for selective photocatalytic CO2 reduction to C2H4. The interconversion between W(V) and W(VI) in W18O49 ensures the stability of Cu(I) during the photocatalytic process. Under light irradiation, the optimal Cu1/W18O49 (3.6-Cu1/W18O49) catalyst exhibits concurrent high activity and selectivity toward C2H4 production, reaching a corresponding yield rate of 4.9µmol g-1 h-1 and selectivity as high as 72.8%, respectively. Combined in situ spectroscopies and computational calculations reveal that Cu(I) single atoms stabilize the *CO intermediate, and the asymmetric Cu─W dual sites effectively reduce the energy barrier for the C─C coupling of two neighboring CO intermediates, enabling the highly selective C2H4 generation from CO2 photoreduction. This work demonstrates leveraging stabilized atomically-dispersed Cu(I) in asymmetric dual-sites for selective CO2-to-C2H4 conversion and can provide new insight into photocatalytic CO2 reduction to other targeted C2+ products through rational construction of active sites for C─C coupling.

Enhanced selective photocatalytic CO2 reduction to CO on AuPd decorated Bi2O2.33 nanosheets

Photocatalytic conversion of carbon dioxide (CO2) into valuable fuels addresses pressing needs for renewable energy and carbon neutrality. However, conventional photocatalytic CO2 reduction on semiconductor is usually limited by sluggish electron kinetics, poor efficiency and low product selectivity. Herein, we developed a bimetallic Au/Pd-decorated Bi2O2.33 ultrathin nanosheet photocatalyst for highly selective CO2 reduction to CO under visible light irradiation. Bi2O2.33 nanosheets self-assembled from nanodots serve as ideal supports for Au/Pd anchoring due to abundant grain boundaries. Systematic characterization reveals the formation of alloyed Au/Pd nanoparticles on the Bi2O2.33 surface, which endowed a superior CO production rate of 436.8 μmol g−1 h−1 with a selectivity of 96.68 % from CO2 photoreduction. Quantum chemical calculations uncover that plasmonic Au/Pd alloys facilitates interfacial charge transfer and CO2 activation to form the CO-yielding intermediate. This work demonstrates an effective strategy for designing bimetallic plasmonic cocatalysts to optimize the photoreduction selectivity and efficiency of semiconductor photocatalysts.

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

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

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.

The cooperative performance of iodo and copper in a Zr-based UiO-67 metal-organic framework for highly selective photocatalytic CO2 reduction to methanol

Photocatalytic CO2 reduction (PCR) to fuels using metal-organic frameworks (MOFs) offers promising solutions for both enhancing energy supply and mitigating global warming. However, research addressing the selectivity towards MeOH production, the role of CO2 uptake in productivity, and the identification of intermediates remains limited. Herein, we present an iodo/copper functionalization strategy for the Zr-based UiO-67 MOF. The resulting bifunctional Cu/I2-Zr-BPDC/BPyDC exhibited remarkable selectivity in light-driven CO2 reduction to MeOH, revealing the first investigation of halogen bonding's effect on PCR. Crucially, Cu/I2-Zr-BPDC/BPyDC surpassed not only pristine Zr-BPyDC, I2-Zr-BPDC, and Cu-Zr-BPyDC, but also boasted the best catalytic performance among reported MOFs. Furthermore, Cu/I2-Zr-BPDC/BPyDC demonstrated a CO2 uptake capacity of 48.6 mg g−1, 1.7 times greater than non-modified Zr-BPyDC, suggesting a direct correlation between CO2 adsorption efficiency and CO2 conversion. In addition to assigning CuII ↔ CuI catalytic cycle, collaborative performance of I and Cu functions in CO2 activation was traced by infrared spectra that elucidate the CI…OCO interaction and Cu…CO2/CuCO2H complex formation. This work provides valuable insights for engineering selective and high-performance PCR catalyst through the rational incorporation of functionalities within MOFs.

Fabrication of Ce-doped UiO-66-NH2 for highly efficient and selective photocatalytic reduction of CO2 to CH4

Defect engineering by creating oxygen vacancies (OVs) and heterogeneous frustrated Lewis acid-base pairs (FLPs) emerged as an efficient strategy to enhance the selective conversion CO2 to CH4. Considering the intrinsic FLPs contained in UiO-66-NH2 (UNH for abbreviation), in this paper, the OVs was introduced therein by fabricating the Ce-doped UNH (denoted as UNH(Ce/Zr)) via one-step solvothermal route. The as-prepared UNH(Ce/Zr) catalyst exhibited the CH4 yield of 31.02 μmol·g−1·h−1 accompanied with the CH4 selectivity of 93 % and satisfying recycling stability. The XRD, SEM, FT-IR, XPS, TG, TPD and NH3 in situ DRIFTS and in situ FT-IR characterization results justified that the UNH(Ce/Zr) possess the obviously increased OVs sites and enhanced Lewis acidic and basic properties. Additionally, the photoelectrochemical characterization results showed that UNH(Ce/Zr)−0.014 efficiently improved photogenerated electron-hole separation efficiency and charge transfer rate. It could be concluded that it was the cooperative action of OVs and FLPs that led to the high CH4 selectivity and CH4 yield.

Unraveling the Transformation from Type-II to Z-Scheme in Perovskite-Based Heterostructures for Enhanced Photocatalytic CO2 Reduction.

The ability to create perovskite-based heterostructures with desirable charge transfer characteristics represents an important endeavor to render a set of perovskite materials and devices with tunable optoelectronic properties. However, due to similar material selection and band alignment in type-II and Z-scheme heterostructures, it remains challenging to obtain perovskite-based heterostructures with a favorable electron transfer pathway for photocatalysis. Herein, we report a robust tailoring of effective charge transfer pathway in perovskite-based heterostructures via a type-II to Z-scheme transformation for highly efficient and selective photocatalytic CO2 reduction. Specifically, CsPbBr3/TiO2 and CsPbBr3/Au/TiO2 heterostructures are synthesized and then investigated by ultrafast spectroscopy. Moreover, taking CsPbBr3/TiO2 and CsPbBr3/Au/TiO2 as examples, operando experiments and theoretical calculations confirm that the type-II heterostructure could be readily transformed into a Z-scheme heterostructure through establishing a low-resistance Ohmic contact, which indicates that a fast electron transfer pathway is crucial in Z-scheme construction, as further demonstrated by CsPbBr3/Ag/TiO2 and CsPbBr3/MoS2 heterostructures. In contrast to pristine CsPbBr3 and CsPbBr3/TiO2, the CsPbBr3/Au/TiO2 heterostructure exhibits 5.4- and 3.0-fold enhancement of electron consumption rate in photocatalytic CO2 reduction. DFT calculations and in situ diffuse reflectance infrared Fourier transform spectroscopy unveil that the superior CO selectivity is attributed to the lower energy of *CO desorption than that of hydrogenation to *HCO. This meticulous design sheds light on the modification of perovskite-based multifunctional materials and enlightens conscious optimization of semiconductor-based heterostructures with desirable charge transfer for catalysis and optoelectronic applications.

Confined bismuth single atoms and nanoparticles dual-sites constructed via reverse etching for CO2 photoreduction to CH4

Synchronizing the directional photogenerated transfer of electrons and regulating the CO2 photocatalytic reduction process are key to achieving the efficient and highly selective photocatalytic reduction of CO2. The design of highly-dispersed active sites and the efficient collaboration of multiple sites are of great importance in attaining the above target. Herein, a reverse etching route was first proposed to confine Bi single atoms and nanoparticles as dual-sites for assisting CO2 photoreduction on TiO2, avoiding the mutual masking of the active sites. The Synergism of the dual-sites achieves the hydrodeoxygenation of * COOH and ushers the directional conversion of CO2 to CH4. Highly dispersed single Bi atoms could induce the transfer of photogenerated electrons, enhance CO2 absorption, and further provide active sites for reducing CO2 to *COOH intermediates. Besides, appropriate Bi nanoparticles could promote the separation and transfer of photogenerated and inhibit the formation of hydroxyl groups; more importantly, they could promote the release of protons, which would further accelerate the conversion of *COOH to CH4. After being integrated, the optimized dual-Bi/TiO2 catalyst achieves a CH4 generation rate of 103.89 μmol·g−1·h−1 with an impressive selectivity of 96.87 % as well as remarkable durability for photocatalytic CO2 reduction. This work provides new insights into developing robust catalysts through the artful design of synergistic catalytic sites for efficient photocatalytic CO2 conversion.

The photo-decomposition and self-restructuring dynamic equilibrium mechanism of Cu2(OH)2CO3 for stable photocatalytic CO2 reduction

Developing suitable photocatalysts and understanding their intrinsic catalytic mechanism remain key challenges in the pursuit of highly active, good selective, and long-term stable photocatalytic CO2 reduction (PCO2R) systems. Herein, monoclinic Cu2(OH)2CO3 is firstly proven to be a new class of photocatalyst, which has excellent catalytic stability and selectivity for PCO2R in the absence of any sacrificial agent and cocatalysts. Based on a Cu2(OH)213CO3 photocatalyst and 13CO2 two-sided 13C isotopic tracer strategy, and combined with in situ diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis and density functional theory (DFT) calculations, two main CO2 transformation routes, and the photo-decomposition and self-restructuring dynamic equilibrium mechanism of Cu2(OH)2CO3 are definitely revealed. The PCO2R activity of Cu2(OH)2CO3 is comparable to some of state-of-the-art novel photocatalysts. Significantly, the PCO2R properties can be further greatly enhanced by simply combining Cu2(OH)2CO3 with typical TiO2 to construct composites photocatalyst. The highest CO and CH4 production rates by 7.5 wt% Cu2(OH)2CO3-TiO2 reach 16.4 μmol g−1h−1 and 116.0 μmol g−1h−1, respectively, which are even higher than that of some of PCO2R systems containing sacrificial agents or precious metals modified photocatalysts. This work provides a better understanding for the PCO2R mechanism at the atomic levels, and also indicates that basic carbonate photocatalysts have broad application potential in the future.

Proton Turnover Dominated Cascade Route for CO2 Photoreduction

AbstractPhotoreduction carbon dioxide (CO2) and water (H2O) into valuable chemicals is a huge potential to mitigate immoderate CO2 emissions and energy crisis. To date, tremendous attention is concentrated on the improvement of independent CO2 reduction or H2O oxidation behaviors. However, the simultaneous control of efficient electron and hole utilization is still a huge challenge due to the complex cascade redox reactions. Here, a proton turnover exists in the whole CO2 photoreduction process is discovered, which is defined as the pivot to concatenate the hole and electron behaviors. As a demonstration of the concept, the efficient activated hydrogen (*H) production centers of copper (Cu) and rapid hydrogenation centers of nickel (Ni) are coupled by an alloying strategy, and the proton turnover behaviors could be directly determined by adjustment of the molar ratios of CuxNiy. Moreover, Cu3Ni1–TiO2 exhibits the highest electron selectivity of 93.7% for methane (CH4) production with a rate of 175.9 µmol g−1 h−1, while Cu1Ni5–TiO2 reaches up to the highest carbon monoxide (CO) electron selectivity and generation rate at 84.4% and 164.6 µmol g−1 h−1, respectively. Consequently, the experimental and theoretical analysis all clarify the predominate proton turnover effect during the overall CO2 photoreduction process, which directly determines the categories and generated efficiency of C‐based products by regulating variable reaction pathways. Therefore, the revelation of the proton turnover pivot could broaden the new sights by bidirectional optimization of dynamics during the overall CO2 photoreduction system, which favors the efficient, selective, and stable photocatalytic CO2 reduction with H2O.

Cayanamide Group Functionalized Crystalline Carbon Nitride Aerogel for Efficient CO2 Photoreduction

AbstractFor photocatalytic CO2 reduction, traditional amorphous polymeric carbon nitride (PCN) has suffered from fast photoexcited electron‐hole recombination and low specific surface area, resulting in low photocatalytic activity. Herein, starting from thermally polymerized PCN, cayanamide groups (─CN) functionalized crystalline carbon nitride (CCN) self‐supporting aerogels are obtained through a molten‐salt and self‐assembly two‐step strategy, which realized efficient photocatalytic CO2 reduction into CO as the main reduction products and O2 as the oxidation product, with CO evolution rate and selectivity reaching 25.7 µmol g−1 h−1 and 93.8%, respectively. It is revealed that the self‐supporting porous aerogel structure can enhance the mass transport of reactants and products, and increase the light absorption ability via multiple photon reflection. With charge carrier separation greatly enhanced in CCN aerogels with high crystallinity as revealed by charge carrier dynamics investigations, theoretical calculations and in situ spectral characterizations evidence that the introduced ─CN groups would act as the active sites for photoreduction of CO2 into CO, with energy barrier greatly reduced for the formation of COOH* intermediates, the rate‐determining step for CO2─to─CO reduction. This work demonstrates a novel and controllable strategy to develop semiconducting polymers with crystal, molecular and morphological structures synergistically modulated for highly efficient and selective photocatalytic CO2 reduction.

One-pot hydrothermal preparation of Ni and I co-doped brookite-anatase TiO2 nanoparticles with remarkably enhanced photoreduction activity of CO2 to CH4

Ni and I co-doped TiO2 nanoparticles with mixed anatase-brookite phase (Ni/I-TiO2) were synthesized by the hydrothermal-calcination method for photocatalytic CO2 reduction with H2O vapor. The I and Ni co-doping, anatase-brookite phase junction, as well as the presence of Ti(III) and Ni(III) endowed the catalyst with promoted visible light absorption, increased reduction ability of photogenerated electrons, facilitated charge separation and migration along with modulated CO2 adsorption mode and capacity, ultimately resulting in boosted photocatalytic activity and product selectivity as compared with those of pure TiO2. The CO, CH4 and O2 yields of the optimized Ni/I-TiO2 reached 3.49, 158.25 and 246.30 μmol/gcat after 15 h of light illumination, which decreased slightly after 9 cycles, and the product selectivity was above 98 % for photocatalytic reduction of CO2 to CH4 with Ni and I co-doping. The in-situ FTIR results with the observation of CH3O and CH3 intermediates confirmed CH4 formation, and the possible mechanism of photocatalytic CO2 reduction over Ni/I-TiO2 was elucidated. This work provides new insights to pursue efficient catalysts for the selective photocatalytic CO2 reduction to CH4.

Brominated metal phthalocyanine-based covalent organic framework for enhanced selective photocatalytic reduction of CO2

Covalent organic frameworks (COFs) have great potential for photocatalytic CO2 reduction, owing to their adjustable structures, porous characteristics, and highly ordered nature. However, poor light absorption, fast recombination of photogenerated electron-hole pairs, and suboptimal coordination conditions have contributed to the hindered efficiency and selectivity observed in photocatalytic CO2 reduction processes. In this work, the integration of bromine (Br) atoms into COFs was achieved through the synthesis process involving nickel (II) tetraaminophthalocyanine (NiTAPc) and 3,6-dibromopyromellitic dianhydride (BPMDA) using a solvothermal approach. The coupling of a porous framework structure alongside the incorporation of Br atoms yields a significant enhancement in photoelectric properties compared to bromine-free COFs. Meanwhile, X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations revealed that the introduction of Br atoms can facilitate the adjustment of the electron configuration around the phthalocyanine unit and diminish the required energy for the photocatalytic reaction. When subjected to visible light irradiation, the NiTAPc-BPMDA COF showcased a CO yield of 148.25 μmol g−1 over a 5-hour period, accompanied by an impressive selectivity of 98%. This work highlights the collaborative influence of phthalocyanines and Br atoms within COF-based photocatalysts, offering an alternative approach for designing and constructing high-performance photocatalysts with elevated yield and selectivity. The synergistic role of phthalocyanines and Br atoms within the COF-based photocatalysts provides an alternative strategy for photocatalysts with high yield and selectivity in the future.

Highly selective photocatalytic CO2 reduction by metal-N4 dynamically generated from atomically dispersed copper

Solar-driven conversion of CO2 into high-value-added chemicals is considered as one of the effective strategies to address global climate change. However, the sluggish charge separation kinetics and poor product selectivity remain the two major bottlenecks restricting photocatalytic CO2 conversion. Herein, we developed an anatase surface modified atomically dispersed Cu (Cu anchored on N-doped carbon skeleton) photocatalyst (TiO2/Cu1NC) based on a “reflux + calcination” method for CO2 photoreduction. Under full spectral illumination, the as-synthesized TiO2/Cu1NC displayed a brilliant CO production rate of 2.59 μmol h−1 (mass of photocatalyst: 5 mg), high selectivity (∼98.5%), and excellent durability using [Ru(bpy)3]Cl2·6H2O as the photosensitizer and triethanolamine as an electron donor. Experiments and density functionalized theory calculations synergistically confirm that the surface-constructed atomically dispersed Cu1NC active sites can accelerate the separation and transfer of photogenerated charge carriers, optimize CO2 adsorption and activation, reduce the formation energy barrier of the key intermediate *COOH during the CO2RR process, and thus enhance the activity and selectivity of CO2RR. This work provides new insights into the surface engineering of atomically dispersed active sites to improve the activity and CO selectivity of CO2 photoreduction.

Prominent COF, g-C3N4, and Their Heterojunction Materials for Selective Photocatalytic CO2 Reduction

New heterojunction materials (HJs) were synthesized in-situ by molecularly bonding the monomers of a triazine-based covalent organic framework (bulk COF) on the template of exfoliated carbon nitride (g-C3N4). The photocatalysts reduced carbon dioxide to carbon monoxide in aqueous dispersions under UV irradiation. The g-C3N4 showed production of 6.50 μmol CO g−1 h−1 and the bulk COF of 2.77 μmol CO g−1 h−1. The CO yield was evaluated in sustainability photoreduction cycles and their CO2 uptake capacity and isosteric heat of adsorption were estimated. All the heterojunction photocatalysts obtained ameliorated CO production rates compared to the bulk COF. Finally, the influence of the Pt co-catalyst on the photocatalytic activities was determined without the addition of any sacrificial agent, and the COF:g-C3N4 heterojunction with the ratio of 1:10 was proven to be a photocatalytic system with an optimum and selective, CO yield of 7.56 μmol g−1 h−1.

Low-coordination transition metal sites on oxygen vacancy enriched strontium titanate-based perovskites enable highly selective photocatalytic CO2 reduction to CH4

The photochemical conversion of CO2 into high-value single hydrocarbon fuels such as CH4 remains a challenge. Here we have prepared a series of perovskites VO-SrTiMO3 (M = Mn, Fe, Co) with rich oxygen vacancies. Among them, Mn-doped perovskite (VO-STMn0.2) exhibited 18.21 μmol g−1 yield and nearly 100 % selectivity for CH4, as well as excellent reproducibility of about 15 h. Through a combination of advanced characterization and theoretical calculations, we found that the low-coordination transition metal site was able to stabilize the critical COOH* and CO* intermediates, thereby altering the reaction pathway to form CH4 instead of CO. Most importantly, this work demonstrated that the relative center between the 2p orbitals of the oxygen atom of the CO2 reduction intermediate and the 3d orbitals of the low-coordination metal site regulates the reaction mechanism of CO2 reduction, offering the possibility of achieving efficient photochemical reduction of CO2.

Embedding CsPbBr3 Quantum Dots into an In2O3 Nanotube for Selective Photocatalytic CO2 Reduction to Hydrocarbon Fuels.

Halide perovskite quantum dots (QDs) are one of the most prospective candidates for photocatalytic CO2 reduction, but their photocatalytic performances are far from satisfactory due to structural instability and severe charge recombination. In this study, we demonstrated a CsPbBr3 QDs/In2O3 hierarchical nanotube (CPB/IO) for efficient CO2 conversion, in which CsPbBr3 QDs were well-dispersed on the In-MOF-derived In2O3 nanotube by a facile self-assembly process. The optimized CPB/IO catalyst displayed an enhanced photocatalytic CO2 performance with a (CO + CH4) generation rate of 16.37 μmol·g-1·h-1 upon simulated solar illumination without a photosensitizer and sacrificial agent, which is 3.59 times stronger than that of pristine CsPbBr3 QDs (4.56 μmol·g-1·h-1). Besides, the modified CsPbBr3 QD catalyst exhibited an obvious increase of CH4 selectivity and excellent stability after four cycles. The unique zero-dimensional (0D)/one-dimensional (1D) heterostructure and matching band potentials between CsPbBr3 and In2O3 supply an intimate interfacial contact, numerous active sites, and effective charge transfer for CO2 photoreduction. This work can inspire the formation of novel halide-perovskite-involving photocatalysts for solar fuel formation.

Ultrathin RuO2/Bi2WO6 and PtO2-Pt/Bi2WO6 heterojunction nanosheets toward efficient photocatalytic CO2 reduction under visible light irradiation

Ultrathin RuO2/Bi2WO6 and PtO2-Pt/Bi2WO6 heterojunction nanosheets with superior (001) crystal planes were successfully constructed by combining a hydrothermal process with photo-deposition technique, which present efficient photocatalytic reduction of CO2 into CO and CH4 under visible light irradiation. Under the irradiation of 420 nm monochromatic light, the apparent quantum yield (AQY) of RuO2/Bi2WO6 reached to 0.21 %, which was about 1.2 times that of PtO2/Pt-Bi2WO6 (0.17 %) and 1.9 times that of pristine Bi2WO6 (0.11 %), respectively. After decorated RuO2 or PtO2-Pt QDs on Bi2WO6 nanosheets to form local heterojunctions including a type II p-n heterojunction RuO2/Bi2WO6 or PtO2/Bi2WO6, as well a Schottky junction Pt/Bi2WO6, RuO2/Bi2WO6 exhibited a higher photocatalytic activity and selectivity of CH4 evolution (33.95 %) than PtO2-Pt/Bi2WO6 (20.9 %), due to the synergetic effect of following factors including enhanced absorption of visible light, improved separation efficiency of charge carrier, reduced charge transfer resistance, enlarged reduction drive ability of photo-induced electrons, accelerated surface catalytic reaction kinetics, and improved specific surface and pore volume. This work provides guidance for designing and developing novel Bi2WO6-based photocatalysts for selective photocatalytic CO2 reduction into target reaction.

Bidirectional host-guest interactions promote selective photocatalytic CO2 reduction coupled with alcohol oxidation in aqueous solution

Existing artificial photosynthesis systems often underperform due to challenges in water oxidation and extensive photogenerated carrier transfer. Herein, we demonstrate that β-cyclodextrin-decorated CdS nanocrystals (CdS-CD) can simultaneously anchor cobalt tetraphenyl porphyrin (CoTPP) catalysts and alcohol reductants onto CdS surfaces through bidirectional host-guest interactions between β-CD and CoTPP/alcohol. This configuration ensures swift electron transfer from CdS to β-CD bonded CoTPP, facilitating CO2 reduction to HCOOH. Results showcase a remarkable yield of 1610 μmol g−1 h−1 and a 96.5% selectivity. Meanwhile, photogenerated holes in CdS are efficiently neutralized by β-CD bonded furfuryl alcohol, achieving a furfural yield of 1567 μmol g−1 h−1 and > 99% selectivity. In contrast, the discrete CoTPP-CdS system achieved a HCOOH yield of only 306 μmol g−1 h−1 and a poor HCOOH selectivity of 46.4%. It was also observed that the CoTPP@CdS-CD system maintained high CO2-to-HCOOH conversion rates when using other alcohols as reductants.