High CO Yield Research Articles

Dual-Fluorinated Ni Single Atom Catalyst for Efficient Artificial Photosynthetic Diluted CO2 Reduction.

The development of efficient photocatalysts to convert dilute CO2 from flue gas into high value-added products is a promising approach to achieving carbon neutrality. In this work, a dual-fluorinated Ni single atom photocatalyst is reported for the photoreduction of diluted CO2 to CO. Under a dilute CO2 (10%) atmosphere, TPB-SA2F-Ni achieves the highest reported CO yield (30344.4µmol g-1h-1) among heterogeneous catalytic systems with a CO selectivity of 98%. Kevin probe force microscopy and photoelectrochemical characterizations indicate that dual-fluorination strategy enhances photoexcited electron transfer between the photosensitizer and photocatalyst by optimizing the conjugated electronic structure. Pore size distribution and CO2 adsorption experiments show that the uniform microporous structure induced by the dual-F site further enhanced the ability of the Ni-N2O2 active site to capture CO2 molecules. Density functional theory calculations indicate that the high CO yield of TPB-SA2F-Ni stems from a lowered energy barrier for *COOH intermediate formation.

Photocatalytic CO₂ Reduction Using Ni(II) and Co(II) Cryptates: Influence of Ionic Liquids and Light Sources

AbstractThe photoreduction of CO2 offers a sustainable route for mitigating atmospheric CO2 levels while producing added value chemicals. This study explores the use of Ni(II) and Co(II) octaazacryptates complexes as catalysts in the presence of different ionic liquids under blue LED and solar light conditions. By employing a systematic approach to vary ionic liquid concentrations and light sources, the catalytic performance was assessed in terms of CO production, H2 production, CO selectivity, turnover number, and photoreaction quantum yield. The findings reveal that ionic liquid 1‐ethyl‐4‐picolinium triflate significantly enhances CO2 reduction efficiency under solar light, with the highest CO yield of 15.75 µmol and CO turnover number of 1575 observed when using 2%w/w of the ionic liquid. Conversely, higher ionic liquid concentrations improved selectivity at the expense of CO production. The experiments conducted under sunlight demonstrated a compromise between selectivity and turnover, with the highest CO turnover number achieved for ionic liquid experiments, but greater selectivity in the absence of ionic liquid. These results underscore the importance of ionic liquid concentration in modulating catalytic performance, while also highlighting the potential of direct sunlight as a sustainable and powerful energy source for scalable, eco‐friendly CO2 photoreduction systems.

Construction of Asymmetric Anion Layer to Accelerate Carrier Reaction Kinetics and Thermodynamically Promote Photocatalytic CO2 Reduction

AbstractThe efficient photocatalytic reduction of CO2 into value‐added chemicals is significantly challenged by the charge carrier separation and transfer kinetics of photocatalysts as well as the thermodynamics of the CO2 reduction process. Herein, it proposes a heterojunction with asymmetric W‐Cl anion layer in Bi2WO6 (abbreviated as BWOC). The asymmetric W‐Cl anion layer results in unbalanced electron density distribution and thus enables to establish atomic‐level donor–acceptor structure as well as larger electrostatic potential in the heterojunction, which facilitate the charge carrier separation and transfer kinetics. Simulation on the intermediates of the CO2 photoreduction process demonstrates that Bi2WO6 with asymmetric W‐Cl anion layer possesses smaller energy barrier for the rate‐determining step of *COOH endothermic formation, and it is thermodynamically more favorable to generate CO as further confirmed by the detection of intermediates over in situ Fourier transform infrared spectroscopy. As a result, BWOC achieved rather high CO yield with the value of 32.11 µmol g−¹ h−¹ which is nearly four times higher than that of pure Bi2WO6. The construction of asymmetric anion layer in this work provides new insights for the design of efficient photocatalytic systems toward CO2 reduction.

Construction of S-Scheme Cs2AgBiBr6/BiVO4 Heterojunctions with Fast Charge Transfer Kinetics Toward Promoted Photocatalytic Conversion of CO2.

Lead-based halide perovskites (LHPs) have been widely explored by researchers in the field of photocatalysis. However, the poor stability and toxicity of LHPs limit their large-scale applications. Here, lead-free Cs2AgBiBr6/BiVO4 (CABB/BVO)-X% (X = 30, 50, 100) S-scheme heterojunction composites are prepared by electrostatic assembly, and their catalytic activity for photoreduction of CO2 is evaluated. After 3h of simulated solar irradiation, the prepared CABB/BVO-50% composites show the highest CO yield and electron consumption rate of 143.59 and 352.22µmol g-1, which are 9.2 and 7.8 times higher than that of CABB alone, respectively. In addition, the prepared CABB/BVO-50% photocatalysts exhibit 81.5% high selectivity for CO. The generation of an internal electric field (IEF) between the two materials and the generation of S-scheme heterojunctions are powerfully confirmed by employing various characterization techniques and DFT calculations. The low carrier recombination rate, bandgap-matched heterointerfaces, and exceptional S-scheme charge transfer mechanism are primarily responsible for the outstanding performance. This work provides new insights into the design of efficient lead-free perovskites-based photocatalytic materials.

Ni‐BDC MOF/MnO2 Composite for Highly Efficient CO2 Photoreduction to CO and CH4 Under Visible Light

AbstractMOF‐based composites with semiconductors offer synergistic effects, such as broader light absorption, improved charge carrier separation, and more active catalytic sites, all of which enhance the overall performance of the MOFs in CO2 reduction. This study presents the development and characterization of a Ni‐BDC MOF/MnO2 composite for photocatalytic CO2 reduction under visible light. The Ni‐BDC MOF with a bandgap of 3.16 eV was integrated with γ‐MnO2, a visible light‐absorbing semiconductor to improve charge separation and extend light absorption. The resulting composite exhibited a reduced bandgap of 2.7 eV, enabling efficient CO2 reduction to CO and CH4. Structural, optical, and electrochemical analyses confirmed the intimate interaction between Ni‐BDC MOF and MnO2, enhancing charge carrier dynamics. The optimized composite achieved high yields of CO (56.97 µmol g⁻¹) and CH4 (23.5 µmol g⁻¹) after 6 h of irradiation, with enhanced stability and minimal electron‐hole recombination. The mechanistic study revealed multiple intermediates involved in CO2 reduction, providing insights into the pathways for CO and CH4 formation. This work offers a sustainable approach to CO2 conversion with potential applications in greenhouse gas mitigation and energy production.

CO2 Photoreduction Improvement by Carbon Nitride Utilizing the Synergism of Na Ion and Cyano Defects.

Conversion of CO2 to high value products was considered as a focused issue towards carbon neutrality. Photocatalysis held the potential to realize the target, and graphitic carbon nitride (g-C3N4) was a competitive candidate. The photocatalytic efficiency of g-C3N4 limited by the weak adsorption of CO2 and easy recombination of charge carriers. Herein, Na ion and cyano defects was induced into g-C3N4 simultaneously using NaHSO3 as alkali molten salt to work out these obstacles. The optimized photocatalyst 3 Na-CN (the weight of NaHSO3 was 1.5 g) exhibited the highest CO yield (21.5 μmol g-1 h-1), which was 5 times than that of pristine g-C3N4 (4.29 μmol g-1 h-1). By means of experiments and characterization, 3 Na-CN displayed better performance in both light utilization and charge separation, which was reflected by the improved photocurrent response, decreased electrochemical impedance, markedly diminished fluorescence intensity, and shortened fluorescence lifetime. This result could be ascribed to the facilitation of electron-hole separation induced by cyano defects, as well as the enhancement in CO2 adsorption and activation mediated by the Na ion. This work offers a new perspective on dual modulation of graphitic carbon nitride and paves the way for the design of CO2 reduction photocatalyst.

Design and Preparation of ZnIn2S4/g-C3N4 Z-Scheme Heterojunction for Enhanced Photocatalytic CO2 Reduction

In this study, a novel Z-scheme heterojunction photocatalyst was developed by integrating g-C3N4 nanoplates into ZnIn2S4 microspheres. X-ray photoelectron spectroscopy analysis revealed a directional electron transfer from g-C3N4 to ZnIn2S4 upon heterojunction formation. Under irradiation, electrochemical tests and electron paramagnetic resonance spectroscopy demonstrated significantly enhanced charge generation and separation efficiencies in the ZnIn2S4/g-C3N4 composite, accompanied by reduced charge transfer resistance. In photocatalytic CO2 reduction, the ZnIn2S4/g-C3N4 composite achieved the highest CO yield, 1.92 and 5.83 times higher than those of pristine g-C3N4 and ZnIn2S4, respectively, with a notable CO selectivity of 91.3% compared to H2 (8.7%). The Z-scheme heterojunction mechanism, confirmed in this work, effectively preserved the strong redox capabilities of the photoinduced charge carriers, leading to superior photocatalytic performance and excellent long-term stability. This study offers valuable insights into the design and development of g-C3N4-based heterojunctions for efficient solar-driven CO2 reduction.

Strong Interfacial Interaction in Polarized Ferroelectric Heterostructured Nanosheets for Highly Efficient and Selective Photocatalytic CO2 Reduction.

Heterojunctions are sustainable solutions for the photocatalytic CO2 reduction reaction (CO2RR) by regulating charge separation behavior at the interface. However, their efficiency and product selectivity are severely hindered by the inflexible and weak built-in electric field and the electronic structure of the two phases. Herein, ferroelectric-based heterojunctions between polarized bismuth ferrite (BFO(P)) and CdS are constructed to enhance the interfacial interactions and catalytic activity. The intrinsic polarization field depending on the ferroelectric state causes significant electrostatic potential difference and energy-band bending. This helps overcome the unsatisfactory redox potential that differs from the classical catalytic mechanism, and synergy from the heterostructure facilitates effective separation and transfer of photogenerated charges with an extended lifetime (>20ns) and significantly enhanced photovoltage (1002 times that of BFO). The optimized charge carrier dynamics allow the heterojunction to achieve a much higher CO yield compared to state-of-the-art ferroelectric-based photocatalysts, and 85.46 and 23.47 times higher than those of pristine CdS and BFO, respectively. Moreover, it maintains an impressive 100% product selectivity together with excellent repeatability and cycling. This work not only sheds light on how a strong inherent polarity promotes the performance of heterojunction photocatalysts but also provides new insights for designing efficient photocatalytic CO2RR.

Direct Synthesis of Topology-Controlled BODIPY and CO2-Based Zirconium Metal-Organic Frameworks for Efficient Photocatalytic CO2 Reduction.

Boron dipyrromethene (BODIPY)-based zirconium metal-organic frameworks (Zr-MOFs) possess strong light-harvesting capabilities and great potential for artificial photosynthesis without the use of sacrificial reagents. However, their direct preparation has not yet been achieved due to challenges in synthesizing suitable ligands. Herein, we reported the first successful direct synthesis of BODIPY-based Zr-MOFs, utilizing CO2 as a feedstock. By controlling synthetic conditions, we successfully obtained two distinct Zr-MOFs. The first, CO2-Zr6-DEPB, exhibits a face-centered cubic (fcu) topology based on a Zr6(μ3-O)4(μ3-OH)4 node, while the second, CO2-Zr12-DEPB, features a hexagonal closed packed (hcp) topology, structured around a Zr12(μ3-O)8(μ3-OH)8(μ2-OH)6 node. Both MOFs demonstrated excellent crystallinity, as verified through powder X-ray diffraction and high-resolution transmission electron microscopy analyses. These MOF catalysts displayed suitable photocatalytic redox potentials for the reduction of CO2 to CO using H2O as the electron donor in the absence of co-catalyst or toxic sacrificial reagent. Under light irradiation, CO2-Zr12-DEPB and CO2-Zr6-DEPB offered high CO yields of 16.72 and 13.91 μmol g-1 h-1, respectively, with nearly 100 % selectivity. CO2 uptake and photoelectrochemical experiments revealed key insights into the mechanisms driving the different catalytic activities of the two MOFs. These BODIPY and CO2-based, light-responsive Zr-MOFs represent a promising platform for the development of efficient photocatalysts.

Direct Synthesis of Topology‐Controlled BODIPY and CO2‐Based Zirconium Metal‐Organic Frameworks for Efficient Photocatalytic CO2 Reduction

AbstractBoron dipyrromethene (BODIPY)‐based zirconium metal–organic frameworks (Zr‐MOFs) possess strong light‐harvesting capabilities and great potential for artificial photosynthesis without the use of sacrificial reagents. However, their direct preparation has not yet been achieved due to challenges in synthesizing suitable ligands. Herein, we reported the first successful direct synthesis of BODIPY‐based Zr‐MOFs, utilizing CO2 as a feedstock. By controlling synthetic conditions, we successfully obtained two distinct Zr‐MOFs. The first, CO2‐Zr6‐DEPB, exhibits a face‐centered cubic (fcu) topology based on a Zr6(μ3‐O)4(μ3‐OH)4 node, while the second, CO2‐Zr12‐DEPB, features a hexagonal closed packed (hcp) topology, structured around a Zr12(μ3‐O)8(μ3‐OH)8(μ2‐OH)6 node. Both MOFs demonstrated excellent crystallinity, as verified through powder X‐ray diffraction and high‐resolution transmission electron microscopy analyses. These MOF catalysts displayed suitable photocatalytic redox potentials for the reduction of CO2 to CO using H2O as the electron donor in the absence of co‐catalyst or toxic sacrificial reagent. Under light irradiation, CO2‐Zr12‐DEPB and CO2‐Zr6‐DEPB offered high CO yields of 16.72 and 13.91 μmol g−1 h−1, respectively, with nearly 100 % selectivity. CO2 uptake and photoelectrochemical experiments revealed key insights into the mechanisms driving the different catalytic activities of the two MOFs. These BODIPY and CO2‐based, light‐responsive Zr‐MOFs represent a promising platform for the development of efficient photocatalysts.

Pyrolysis/Non-thermal Plasma/Catalysis Processing of Refuse-Derived Fuel for Upgraded Oil and Gas Production

AbstractRefuse-derived fuel (RDF) produced from the processing of municipal solid waste (MSW) has a high content of biomass and plastics. Pyrolysis of RDF produces a bio-oil which is highly oxygenated, viscous, acidic with a high moisture content and unsuitable for direct use in conventional combustion systems and consequently requires upgrading. A novel process of pyrolysis with non-thermal plasma/catalysis has been developed to produce de-oxygenated bio-oils and gases from RDF. The volatiles from the pyrolysis stage are passed directly to a non-thermal plasma/catalytic reactor where upgrading of the pyrolysis volatiles takes place. Detailed analysis of the product oils and gases is presented in relation to process conditions and in the presence of different catalysts (TiO₂, MCM-41, ZSM-5, and Al₂O₃). Even in the absence of a catalyst, the presence of the non-thermal plasma resulted in high yields of CO and CO₂ gases and reduced bio-oil oxygen content, confirming deoxygenation of the RDF pyrolysis volatiles. The addition of catalysts MCM-41 and ZSM-5 generated the highest yields of CO, CO₂, and H₂ due to the synergy between catalyst and plasma. The catalysts ranked in terms of total oxygenated oil yield are as follows: MCM-41 < ZSM-5 < TiO₂ < Al₂O₃. Pyrolysis of RDF produces an oil containing oxygenated species from biomass and hydrocarbon species from plastics. The non-thermal plasma generates high energy electrons which generate radicals and intermediates from the pyrolysis volatiles which synergistically interact with the catalysts to enable deoxygenation of the oxygenated hydrocarbons through decarboxylation and decarbonylation reactions. Graphical Abstract

Fabrication of a CuS-cocatalyst-supported g-C3N4 nanosheet composite photocatalyst with improved performance in the photocatalytic reduction of CO2.

Carbon dioxide (CO2) is not only a greenhouse gas but also an abundant carbon resource. By using solar energy to reduce CO2 into high-value hydrocarbons via photocatalysis, we can mitigate the greenhouse effect and enable energy recycling. In this paper, a two-step calcination process was employed to thermally exfoliate graphite-phase carbon nitride (g-C3N4) into ultrathin nanosheets, after which the CuS co-catalyst was loaded onto the g-C3N4 surface using a one-step hydrothermal method. The ultrathin nanosheet structure of g-C3N4 can increase the specific surface area of the composite material and improve the anchoring of active components and CO2 adsorption sites. CuS, acting as a co-catalyst, can capture photogenerated electrons from the g-C3N4 conduction band, thereby enhancing the separation and migration of photogenerated charges. Moreover, the interfacial charge transfer (IFCT) mechanism of CuS enhances the efficiency of separating photogenerated electrons and holes. The prepared 10CuS/g-C3N4 composite photocatalyst, loaded with 10 wt% CuS, has significantly improved CO2 photoreduction performance. The highest CO yield reached 15.34 μmol g-1. This work provides guidance for developing low-cost artificial photosynthesis to utilize CO2 as a resource.

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.

Co-doped bismuth vanadate/zinc tungstate heterojunction with dual internal electric fields for efficient photocatalytic reduction of carbon dioxide

Co-doped bismuth vanadate/zinc tungstate heterojunction with dual internal electric fields for efficient photocatalytic reduction of carbon dioxide

Bimetallic NiCu catalyst derived from spent MOF adsorbent for efficient photocatalytic CO2 reduction

Bimetallic NiCu catalyst derived from spent MOF adsorbent for efficient photocatalytic CO2 reduction

Closing the loop: Biochar-supported nickel catalyst for efficient hydrogen-rich syngas production

Closing the loop: Biochar-supported nickel catalyst for efficient hydrogen-rich syngas production

Oxygen-bridged Schottky junction in ZnO–Ni3ZnC0.7 promotes photocatalytic reduction of CO2 to CO: Steering charge flow and modulating electron density of active sites

Oxygen-bridged Schottky junction in ZnO–Ni3ZnC0.7 promotes photocatalytic reduction of CO2 to CO: Steering charge flow and modulating electron density of active sites

Pulsed laser induced plasma and thermal effects on molybdenum carbide for dry reforming of methane

Dry reforming of methane (DRM) is a highly endothermic process, with its development hindered by the harsh thermocatalytic conditions required. We propose an innovative DRM approach utilizing a 16 W pulsed laser in combination with a cost-effective Mo2C catalyst, enabling DRM under milder conditions. The pulsed laser serves a dual function by inducing localized high temperatures and generating *CH plasma on the Mo2C surface. This activates CH4 and CO2, significantly accelerating the DRM reaction. Notably, the laser directly generates *CH plasma from CH4 through thermionic emission and cascade ionization, bypassing the traditional step-by-step dehydrogenation process and eliminating the rate-limiting step of methane cracking. This method maintains a carbon-oxygen balanced environment, thus preventing the deactivation of the Mo2C catalyst due to CO2 oxidation. The laser-catalytic DRM achieves high yields of H2 (14300.8 mmol h−1 g−1) and CO (14949.9 mmol h−1 g−1) with satisfactory energy efficiency (0.98 mmol kJ−1), providing a promising alternative for high-energy-consuming catalytic systems.

Syntheses of heterometallic organic frameworks catalysts via multicomponent postmodification: For improving CO2 photoreduction efficiency

Syntheses of heterometallic organic frameworks catalysts via multicomponent postmodification: For improving CO2 photoreduction efficiency

Development of Plasmonic Attapulgite/Co(Ti)Ox Nanocomposite Using Spent Batteries toward Photothermal Reduction of CO2

The rapid development of the battery industry has brought about a large amount of waste battery pollution. How to realize the high-value utilization of waste batteries is an urgent problem to be solved. Herein, cobalt and titanium compounds (LTCO) were firstly recovered from spent lithium-ion batteries (LIBs) using the carbon thermal reduction approach, and plasmonic attapulgite/Co(Ti)Ox (H-ATP/Co(Ti)Ox) nanocomposites were prepared by the microwave hydrothermal technique. H-ATP had a large specific surface area and enough active sites to capture CO2 molecules. The biochar not only reduced the spinel phase of waste LIBs into metal oxides including Co3O4 and TiO2 but also increased the separation and transmission of the carriers, thereby accelerating the adsorption and reduction of CO2. In addition, H-ATP/Co(Ti)Ox exhibited a localized surface plasmon resonance effect (LSPR) in the visible to near-infrared region and released high-energy hot electrons, enhancing the surface temperature of the catalyst and further improving the catalytic reduction of CO2 with a high CO yield of 14.7 μmol·g−1·h−1. The current work demonstrates the potential for CO2 reduction by taking advantage of natural mineral and spent batteries.