Photocatalytic Reduction Process Research Articles

Insight into Antiviral Activity of Ag/TiO2 Nanocomposites Against Influenza H1N1 Virus and Its Antiviral Mechanism.

Synthesis and characterization of silver (Ag)/titanium dioxide (TiO2) nanocomposite (ATA) to investigate its antiviral activity against the H1N1 influenza virus and antiviral mechanisms. A water-dispersible ATA was prepared by a photocatalytic reduction process from AgNO3 and TiO2. The characterization of ATA was performed by ultraviolet-visible spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy. The antiviral activities and the antiviral mechanism of ATA were investigated in detail by light microscopy, transmission electron microscopy and biological techniques such as cell cytotoxicity, 50% tissue culture infectious dose detection, western blot and reverse transcription-polymerase chain reaction. These results showed the successful synthesis of ATA nanocomposite with uniform particle size and distribution. It demonstrated the highly efficient antiviral activity of ATA in a dose- and time-dependent manner, as indicated by the reduction of viral titer and the reduction of cytopathic effects caused by viral infection. In the presence of ATA, the structure of the H1N1 influenza virus is directly destroyed and even disintegrated, with the damaged surface membrane proteins and fuzzy contour. It reduces the infection efficiency of influenza by suppressing the activity and expression of hemagglutinin and neuraminidase. The results of mechanistic studies suggested that ATA nanocomposite primarily interferes with virus attachment to viral receptors on the cell surface. Our study suggests that ATA may be a good antiviral candidate against the influenza virus. Compared with AgNPs alone, our synthesized ATA nanocomposites can achieve similar viral inactivation rates using only a much smaller concentration of AgNPs, greatly reducing the amount of AgNPs and their potential side effects. It has great practical value for attaching ATA to the high-efficiency particulate air network in the air purifier, which can kill the virus attached to it and limit its spread.

Self-standing Z-scheme structured heterogeneous nanosheet arrays of ZnIn2S4/cobalt porphyrin sulfonate for bifunctional photocatalytic carbon dioxide reduction and antibacterial

Photocatalytic CO2 reduction for solar fuel generation and photocatalytic sterilization are highly desired green routes for sustainable environmental purification. Herein, a bifunctional self-standing nanosheet array of Z-scheme structured inorganic–organic heterojunction is synthesized via in-situ growth of ZnIn2S4 (ZIS) on carbon cloth (CC) followed by self-assembly with cobalt porphyrin (meso-tetra(4-sulfonatophenyl) porphyrin, CoTPPS). The obtained CC-ZIS-CoTPPS performed well in the photocatalytic CO2 reduction and antibacterial processes simultaneously in a portable photocatalytic system with a negligible amount of solution. Specifically, the optimized CC-ZIS-CoTPPS demonstrates more than 140 times enhanced CO evolution than pristine CoTPPS. Experimental and theoretical results imply that the enhanced photocatalytic CO2 reduction is associated with elevated light absorption, promoted charge separation, and improved CO2 activation in the inorganic–organic Z-scheme heterojunction. In addition, the self-standing nanosheet array possesses a mechanical cutting effect, which can kill bacteria adhering to the surface even in dark conditions. Moreover, CC-ZIS-CoTPPS achieved a 100 % killing rate under visible light irradiation by synergistically chemical and mechanical sterilization. Furthermore, CC-ZIS-CoTPPS exhibits efficient bifunctional photocatalytic photocatalytic CO2 reduction coupled with in-situ sterilization. This work presents an atomic perspective for developing innovative bifunctional photocatalysts, which hold great potential in portable devices to alleviate energy and environmental crises.

Rapid Charge Transfer Endowed by Hollow‐structured Z‐Scheme Heterojunction for Coupling Benzylamine Oxidation With CO2 Reduction

AbstractIn the field of photocatalysis, ultrafast electron transfer at the interface is the key factor affecting photocatalytic activity. Herein, ultrafast carrier transport is achieved through constructing a Z‐scheme heterojunction of CoSe@Zn0.5Cd0.5S (CoSe@ZCS), which is prepared by in situ growth of ZCS on the ZIF‐67‐derived hollow CoSe. The ultrafast charge transfer at the Z‐scheme heterojunction interface is verified by advanced fs‐transient absorption, which provides vital evidence for the specific mechanism of photocatalytic charge transfer. In addition, the presence of key intermediates (*COOH and C═N) is detected by in‐situ FTIR spectroscopy, which further clarified the mechanism of coupling benzylamine oxidation with CO2 photoconversion. DFT calculations also confirm that the Z‐scheme heterojunction effectively reduces the energy barrier of the rate‐limiting step of *COOH formation, facilitating the photocatalytic CO2 reduction process of ZCS. Benefiting from the ultrafast electron transfer at the interface of the Z‐scheme heterojunction, CoSe@ZCS exhibits excellent bifunctional photocatalytic performance. This work lays the foundation for further exploration of the charge transfer mode at the heterojunction interface to facilitate solar‐driven energy conversion.

Metal Center-Tuned Photocatalytic Carbon Dioxide Reduction for Frameworks with the Tetraphenylethene-Imidazole Ligand.

As heterogeneous photocatalysts that can effectively transform CO2 to CO, two MOFs with different metal centers, namely, [M(tipe)(H2O)2](ClO4)2·solvent (M = Ni named as Ni-MOF and M = Co referred to as Co-MOF), were synthesized by reactions of 1,1,2,2-tetrakis(4-(imidazole-1-yl)phenyl)ethene (tipe) with the corresponding metal perchlorate. Both Ni-MOF and Co-MOF have 3D structures, in which the metal centers have the same coordination environment with the N4O2 donor set. Driven by visible light, the CO production catalyzed by Co-MOF is 6734.1 μmol g-1 with 45.3% selectivity, and in contrast, Ni-MOF has 4601.3 μmol g-1 CO production with 97.6% selectivity in 5 h. Through photoelectrochemical characterization, DFT calculations, and in situ FT-IR measurements, the photocatalytic CO2 reduction process catalyzed by Ni-MOF and Co-MOF was investigated. The results show that the metal center of the MOF is crucial for photocatalytic CO2 reduction. This work offers an innovative approach for controlling the performance of photocatalytic CO2 reduction through tuning the metal centers of architectures.

Enhancing degradation of novel brominated flame retardants by sulfate modified C3N4: Synergistic effect of photocatalytic oxidation and reduction processes

Novel brominated flame retardants (NBFRs) pose serious risks to aquatic organisms and human health due to their persistence and toxicity. Herein, sulfate ions (SO42-) decorated C3N4 (SO42-@CN) photocatalyst material was synthesized for the rapid degradation of NBFRs by a synergistic effect of photocatalytic oxidation and reduction reactions. Compared with bare C3N4, the SO42-@CN exhibited efficient photocatalytic NBFRs removal performance. The degradation rates constant of hexabromobenzene and pentabromotoluene by SO42-@CN were 0.177 and 0.0906 min-1, respectively, which were 2.9 and 6.7 times higher than that by C3N4. It was confirmed that SO42-@CN could generate more active substances (such as sulfate radicals, and hydroxyl radicals) and promote the oxidation of NBFRs. Meanwhile, SO42- accelerated the separation of photogenerated electron-holes by promoting the formation of hydrogenated structures, allowing more photogenerated electrons to participate in the debromination reduction process. This work provides a new insight for the practical application of visible light driven photocatalytic technology in NBFRs residues degradation.

Bimetallic Fe, Co-Modified TiO2 Derived from NH2-MIL-125(Ti) as an Efficient Photocatalyst for N2 Fixation

The conversion of nitrogen (N2) and water (H2O) into NH3 by photocatalysis under ambient conditions has been considered an environmentally friendly strategy. However, developing effective catalysts for N2 fixation is still challenging. Herein, we report a bimetallic JH Fe, Co/TiO2 derived from NH2-MIL-125(Ti) by the fast Joule heating (FJH) method for visible–light–driven catalytic N2 fixation. It was found that the photocatalytic N2 reduction efficiency of bimetallic FC@TiO2-JH was improved, enabling an NH3 yield rate of 110.14 µmol g−1 h−1 without any sacrificial agents. Furthermore, the rate was higher than those of Fe@TiO2-JH and Co@TiO2-JH, suggesting that the synergistic effect between Fe and Co broke the electronic equilibrium and increased the center of its d-band, enhancing electronic feedback to the antibonding π* orbitals of N2 while weakening the bonding energy of N≡N. Meanwhile, the rate was about 2.75 times higher than that of FC@TiO2-TF, which was calcined in a tube furnace. It is assumed that FJH might lead to the formation of lattice defects, leading to localized charge deficiency, enhanced carrier separation, and transport. Thus, doping of Fe and Co synergistically interacted with the defects produced from FJH, facilitating the photocatalytic reduction process. As detected, it had a greater ability to separate hole–electron pairs and transferred electrons to adsorbed N2 at faster rates. Our work demonstrates a prospective strategy for designing bimetallic catalysts derived from NH2-MIL-125(Ti) for N2 fixation.

GFP Chromophore Integrated Conjugated Microporous Polymers toward Bioinspired Photocatalytic CO2 Reduction to CO.

The development of highly active, durable, and low-cost metal-free catalysts for the photocatalytic CO2 reduction reaction (CO2RR) is an efficient and environmentally friendly solution to address significant problems like global warming and high energy demand. In the present study, we have demonstrated the design and synthesis of a donor-acceptor based conjugated microporous polymer (CMP), TPA-GFP, by integrating an electron donor, tris(4-ethynylphenyl)amine (TPA), with a green fluorescent protein chromophore analogue (Z)-4-(2-hydroxy-3,5-diiodobenzylidene)-1-(4-iodophenyl)-2-methyl-1H-imidazol-5(4H)-one (o-HBDI-I3) (GFP). In comparison to nondonor 1,3,5-triethynylbenzene (TEB) based TEB-GFP CMP, photocatalytic CO2 reduction using donor-acceptor based TPA-GFP CMP displays a 3-fold increment of CO production yield with a maximum CO yield of 1666 μmol g-1 at 12 h. Further, the CO selectivity increases significantly from a mere 54% in TEB-GFP to an impressive 95% in TPA-GFP. The impressive CO2 reduction efficiency and selectivity for TPA-GFP can be attributed to the efficient light-harvesting capability and facile charge separation and migration through donor-acceptor building units of the CMP. The mechanistic aspect of the photocatalytic CO2 reduction process is explored using in situ DRIFTS and DFT calculation, and a plausible photocatalytic mechanism is proposed.

Magnetic doping engineering in perovskite microcrystals for boosted photocatalytic CO2 reduction

Conversion of carbon dioxide into value-added chemicals through sunlight is a promising approach to reducing our reliance on fossil fuels. Spin provides another freedom to manipulate the photocatalytic CO2 reduction (CO2RR) process and enhance the corresponding properties of optoelectronic applications. In this work, improved photocatalytic CO2RR efficiency was obtained by manipulating spin-polarized species in inorganic halide perovskite microcrystals (MCs) with the introduction of manganese cations (Mn2+) and an employment of a magnetic field. Mn2+-doped CsPbBr3 MCs were prepared through self-assembly process, where Mn2+ is incorporated into CsPbBr3 matrices successfully. Introducing Mn2+ into CsPbBr3 matrices not only induces structural change but also generates new emission band as well as magnetic properties. Thereby, Mn2+-doped CsPbBr3 MCs show significantly enhanced photocatalytic CO2RR properties in contrast with pristine samples (the CO yield is significantly elevated from 22.1 to 41.9 μmol/g in Mn2+-doped CsPbBr3 MCs), as they generate spin-polarized electrons with the introduction of Mn2+. Remarkably, the photocatalytic CO2RR of Mn2+-doped CsPbBr3 MCs is greatly improved under the employment of a magnetic field, achieving 5.0 times higher performance compared to pristine CsPbBr3 MCs when the magnetic field strength is 300 mT. This enhancement is experimentally demonstrated by using magnetic circular dichroism spectroscopy. The increased photocatalytic CO2RR efficiency of Mn2+-doped CsPbBr3 MCs stems from the cooperative doping of Mn2+ and the application of magnetic fields, which generates more spin-polarized photoexcited carriers, thereby leading to extended carrier lifetime and reduced recombination process. These findings demonstrate that introducing spin into optoelectronic semiconductors is a powerful approach to enhancing photocatalytic CO2RR efficiency.

Tailoring three-dimensional conjugated microporous polymers for photo-enhanced gold extraction

Extracting gold from discarded electronic devices can alleviate the growing environmental problems associated with e-waste and provide a sustainable avenue for the secondary utilization of precious metal resources. Unfortunately, viable green recycling methods have not yet been implemented beyond the large-scale incineration of electronic circuit boards, mainly due to the lack of emerging strategies for efficient gold extraction. It is foreseeable that using green photocatalytic technology to extract gold can provide alternative to existing strategies. Herein, we explore the application of D-π-A-type thiazole-functionalized three-dimensional (3D) conjugated microporous polymer (CMP) (BTD-TEP) for photo-enhanced gold extraction from e-waste. With a large specific surface area, abundant high-affinity sites, good chemical stability, and excellent photocatalytic activity, BTD-TEP can be used as an advanced platform for selective extraction and photocatalytic reduction of gold, thus exhibiting a breakthrough gold recovery capacity (3217.8 mg/g). In the dark, BTD-TEP can selectively extract gold through thiazole motifs integrated on the highly accessible 3D skeleton. Meanwhile, the construction of a highly conjugated 3D D-π-A framework significantly increases the exposure of the catalytic center, enhances the photocatalytic activity of BTD-TEP, and allows for an additional gold photocatalytic reduction process under visible light, which greatly improves the recovery capacity and kinetics.

The cooperative p-n heterojunction and Schottky junction in Au-decorated hierarchical CuS@SnS2 hollow cubes for boosted charge transport and CO2 photoreduction

During the photocatalytic CO2 reduction process, fast charge transport, abundant active sites, and high visible light utilization in photocatalysts are key to achieving excellent CO2 conversion efficiency. In this work, we have designed and prepared hierarchical CuS@SnS2p-n heterostructure hollow cubes for photocatalytic CO2 reduction. First, a monolayer of CuS was in situ generated on the pre-prepared Cu2O cubes to construct core–shell Cu2O@CuS cubes by sulfidation of Cu2O cubes. The following etching process led to the formation of CuS hollow cubes. Finally, the hierarchical CuS@SnS2p-n heterostructure hollow cubes were obtained by growing SnS2 nanosheets on the CuS hollow cubes. The prepared CuS@SnS2p-n heterostructure hollow cubes showed an improved photocatalytic CO2 reduction activity compared with the bare CuS and SnS2 control samples. The p-n heterojunction formed between SnS2 and CuS as well as its hollow structure enhanced the charge carrier separation efficiency and the light absorption capacity of the hybrid catalyst. Furthermore, after the decoration of Au nanoparticles, the formed Schottky junction further discouraged the charge carrier recombination. Thus, the cooperative p-n heterojunction and Schottky junction greatly facilitated photocatalytic CO2 reduction, and exhibiting the maximum CO and CH4 yields of 140.1 and 77.5 μmol g−1 h−1, respectively. This work presents an efficient design of high-performance catalysts for photocatalytic CO2 reduction.

Rationally Designed S-Scheme CeO2/g-C3N4 Heterojunction for Promoting Visible Light Driven CO2 Photoreduction into Syngas.

Exploring low-cost visible light photocatalysts for CO2 reduction to produce proportionally adjustable syngas is of great significance for meeting the needs of green chemical industry. A S-Scheme CeO2/g-C3N4 (CeO2/CN) heterojunction was constructed by using a simple two-step calcination method. During the photocatalytic CO2 reduction process, the CeO2/CN heterojunction can present a superior photocatalytic performance, and the obtained CO/H2 ratios in syngas can be regulated from 1 : 0.16 to 1 : 3.02. In addition, the CO and H2 production rate of the optimal CeO2/CN composite can reach 1169.56 and 429.12 μmol g-1 h-1, respectively. This superior photocatalytic performance is attributed to the unique S-Scheme photogenerated charge transfer mechanism between CeO2 and CN, which facilitates rapid charge separation and migration, while retaining the excellent redox capacity of both semiconductors. Particularly, the variable valence Ce3+/Ce4+ can act as electron mediator between CeO2 and CN, which can promote electron transfer and improve the catalytic performance. This work is expected to provide a new useful reference for the rational construction of high efficiency S-Scheme heterojunction photocatalyst, and improve the efficiency of photocatalytic reduction of CO2, promoting the photocatalytic reduction of CO2 into useful fuels.

Achieving Overall Carbon Utilization from Organic Wastewater to Recover Solar Syngas via an Artificial Carbon Cycling System

AbstractBuilding artificial carbon cycling systems for the direct conversion of wastewater into value‐added solar fuels using renewable solar energy can contribute to achieving carbon neutrality. Herein, a bifunctional photocatalyst comprising three‐dimensionally ordered Ti3C2Tx/TiO2 nanoflowers is exploited for tandem carbon cycling systems to achieve efficient organic wastewater treatment with simultaneous CO2 resourcing. The highest efficiency is achieved by using the optimal Ti3C2Tx/TiO2 photocatalyst to treat simulated wastewater containing rhodamine B (RhB), with an enhanced primary CO production rate of 10.02 µmol g−1 h−1 and RhB degradation efficiency of 77.6% after 1 h of illumination in an anoxic environment. The CO/H2 ratio of the produced syngas can be readily tuned from 0.95 to 1.86 by adjusting the Ti3C2Tx content. Mechanistic studies based on DFT, in situ DRIFTS, and LC‐MS2/IC reveal that the coupled photocatalytic RhB degradation and CO2 reduction processes collectively undertake *HCOO intermediate coverage. This phenomenon triggers the sustainable and simultaneous conversion of *CO2 and *HCOO into CO under mild conditions and crosses the key rate‐limiting step of CO2‐to‐CO conversion, thereby achieving overall carbon utilization from organic wastewater treatment. This study offers in‐depth insights into the design and mechanisms of highly effective carbon utilization in artificial carbon cycling systems.

Mott–Schottky heterostructural TiO2@Ag@AgBr nanohybrids for efficient photocatalytic degradation of Cr (VI) and enhanced on-site SERS detection

In the study, a novel ternary composite TiO2@Ag@AgBr was successfully prepared by surface modification of complete Ag layer and AgBr particles for photocatalytic degradation of representative heavy metal ions Cr (VI) and on-site Surface-enhanced Raman spectroscopy (SERS) detection of the Cr (VI) reduction process. The Mott–Schottky heterojunction contained structure exhibited remarkable photocatalytic ability for heavy metal ions Cr (VI) by tuning the ratio of Ag and AgBr, which could reduce Cr (VI) ions within 30 min and the reaction rate constant is 0.12 min−1. The remarkable photo-reduction performance is attributed to synergistic effect among the various components: the AgBr decorated on the surface of TiO2@Ag could significantly enhance the absorption of visible light and generate numerous photoexcited electrons and holes. Furthermore, the complete Ag layer was constructed on the TiO2 microspheres surface to form heterojunctions in the photocatalytic system by in-situ deposition of AgNO3. Mott–Schottky junctions formed between AgBr/Ag and Ag/TiO2 interface which could extend the charge transfer pathway and facilitate separation of photoexcited electrons and holes. The plasmonic metal layer of nano Ag could generate significant surface plasmon resonance (SPR) effect which not only enhanced the absorption of visible light but also exhibited remarkable SERS effect for probe molecules. And an amazing detection limit of 1 × 10–10 M could be obtained when using crystal violet (CV) as probe molecules. In addition, the SERS substrates exhibited significant linear relationship between concentration and SERS signal intensity which ensures the accuracy of quantitative analysis and monitoring photoreduction process. The substrates have good cycling stability, enabling it to be reused for SERS detection many times. Thus, the excellent photocatalytic and SERS performance of Mott–Schottky hetero-structural TiO2@Ag@AgBr substrates shows great potential toward rapidly photocatalytic removal Cr (VI) ions and SERS on-site detection reduction process of Cr (VI) in waste water, which is of great significance to environmental protection and ecological restoration.

Exploring kinetics and mass transfer in photocatalytic CO2 reduction: Impact of photocatalyst loading and stirrer speed

CO2 photocatalytic reduction is a potential and promising technology to reduce the level of the greenhouse gas in the atmosphere but also as an alternative and renewable fuel resource. However, the products yield of the reaction is still low and the identification of the optimal operating conditions that affect the process are still needed to be determined. This study investigates the impact of key operational parameters, specifically photocatalyst concentration and stirring speed, on the photocatalytic reduction of CO2 in a slurry batch photoreactor utilizing synthesized TiO2. A simplified photocatalytic kinetic model, incorporating the radiation field within the photoreactor, was developed, considering mass transfer from liquid to gas phase for the primary detected reaction products (CO, CH4, and H2). The proposed models elucidate the influence of different operating conditions on product yields. Stirring speed, controlled by a magnetic stirrer, impacts the gas–liquid mass transfer rate. Increased liquid phase stirring speed ensures faster species transport to the gas phase, with a diminishing effect beyond 900 rpm. TiO2 photocatalyst mass concentration influences the available total active surface and irradiation absorbance in the photoreactor volume. Optimal product yields were observed at the lowest tested photocatalyst concentration (0.5 g · L-1), indicating improved irradiation distribution and reduced particle agglomeration, resulting in higher available active surface for the reaction. The calculation model successfully predicted product yields even with lower photocatalyst concentration of 0.25 g · L-1, with marginal increases in predicted yields. These findings provide valuable insights for scaling up and optimizing the CO2 photocatalytic reduction process, offering a foundation for future research.

Enhanced photocatalytic CO2 reduction activity on the novel Z-scheme Co-MOF/Bi2MoO6 to form CO and CH4

Herein, a novel Z-scheme Co-MOF/Bi2MoO6 was synthesized by in-situ growth method. The photocatalytic CO2 reduction effect of Co-MOF/Bi2MoO6 was significantly improved, and the formation rates of CO and CH4 reached 19.76 and 8.24 μmol·g−1·h−1, which corresponded to 1.61 and 2.38 times of Co-MOF (CO: 12.31 μmol·g−1·h−1) and Bi2MoO6 (CH4: 3.46 μmol·g−1·h−1), respectively. The increased photocatalytic activity of Co-MOF/Bi2MoO6 resulted from the enhanced visible light capture capability and the Z-scheme heterojunction formed among Co-MOF and Bi2MoO6, which promoted the efficient separation of photogenerated carriers while retaining the highest redox capacity. The Z-scheme charge transfer direction of Co-MOF/Bi2MoO6 was confirmed by DRS, XPS, ESR, UPS, and the photocatalytic reaction mechanism was explained. In addition, the active substances and intermediates of Co-MOF/Bi2MoO6 in the photocatalytic CO2 reduction process were investigated using ESR and in-situ FT-IR. The work offers a idea for building MOFs-based heterojunctions to improve the effect of photocatalytic CO2 reduction.

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

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

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

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

Developed Photocatalytic Cotton Fabric with Agricultural By-Products Tea Saponins for Accelerating Aqueous Chromium(VI) Reductive Removal

ABSTRACT In order to achieve the goal of preparing functional textiles using tea saponin, in this work, carboxymethylated tea saponin (CTS) was used to modify cotton fabrics by an industrial rolling and baking process, and then functional textiles could be obtained after coordination with Fe3+, which could remove Cr species from water by photocatalytic reduction and adsorption processes. High CTS concentrations and higher treatment temperatures led to an increase in the carboxyl group content (QCOOH) and Fe content (QFe) of the obtained Fe-CTS-Cotton. The increase in the QFe value of the functional textiles favored the photocatalytic reduction of Cr(VI). Fe-CTS-Cotton with high QCOOH values showed excellent adsorption performance for the generated Cr(III) ions during the adsorption process. Therefore, the high photocatalytic reduction efficiency and strong Cr(III) ion trapping ability were the reasons for the recycling of Fe-CTS-cotton as a hybrid photocatalyst for enhanced removal of Cr(VI).

Double defects cooperatively mediated BiOClBr-OV for efficient round-the-clock photocatalytic CO2 reduction

In recent years, the production of high-value solar fuels through photocatalytic reduction of CO2 has received significant attention. However, the low photocatalytic activity and intermittent nature of solar light contributing to low production rates have hindered its large-scale application. This study successfully constructed BiOClBr-OV with two defects (Cl/Br substitution, oxygen vacancy), which not only enhanced the catalytic activity but also opened the door to round-the-clock photocatalytic reduction of CO2. Under visible light exposure, the double defects exhibit a synergistic enhancement effect and outstanding electron storage capacity, resulting in 6.8 times and 34.2 times increase in the photocatalytic activity and electron storage capacity, respectively, compared to the pristine BiOCl. Additionally, BiOClBr-OV with surface oxygen defects exhibits frustrated Lewis pair (FLP) catalytic behavior, effectively changing the adsorption mode of CO2 and enhancing its activation ability. Simultaneously, the unsaturated surface Bi ions of BiOClBr-OV are the electron storage centers, achieving the three-in-one combination of adsorption sites, FLP active sites, and electron storage sites, leading to excellent photocatalytic activity. Finally, the catalytic mechanism and possible reaction pathways are thoroughly explained through in-situ technologies and density functional theory (DFT) calculations. This work introduces a novel multi-sites unified catalyst design strategy, providing deep insight into the photocatalytic CO2 reduction process and making the application of Bi-based semiconductors in round-the-clock photocatalysis possible.

Addressing the competing adsorption bottleneck in photoreduction of CO2 using a hydrophilic-hydrophobic heterojunction photocatalyst

Solar powered conversion / reduction of carbon dioxide into value added chemicals has been identified as one of the foremost challenges for materials science in the 21st century. Despite extensive research, product yield remained low and one of the primary factors has been the issue of competing adsorption of CO2 and water vapour on the catalyst surface. In this work we employ reduced graphene oxide wrapped TiO2 nanotubes (TiO2 - rGO) as a heterojunction photocatalyst and demonstrate that UV irradiation induces hydrophilicity on the TiO2 surface and, hydrophobicity on the rGO surface. The resulting photocatalyst shows 25 % higher yield of methane over that of untreated photocatalyst. Hence, UV irradiation induced tailoring of the hydrophilicity yields selective adsorption sites for the CO2 and water vapour leading to a significant enhancement of the methane yield through photocatalytic reduction process.