The photo-enzyme hybrid system presents a promising approach for the selective conversion of CO2 into valuable chemicals. However, its high dependence on the expensive coenzyme nicotinamide adenine dinucleotide reduced form (NADH), coupled with the need for external electron mediators and highly active photocatalysts, limits its widespread application. Here, we developed a gold nanocapsule—formate dehydrogenase (FDH) hybrid system for in situ NADH regeneration to facilitate the light-driven conversion of CO2 to formate. The results demonstrated that gold nanocapsules (Au NCPs), in conjunction with triethanolamine (TEOA), protected 83.67% of NADH from photodegradation. Under light-driven conditions with TEOA as the electron donor and without external electron mediators, the Au NCPs catalyzed in situ NADH regeneration, achieving a regeneration yield of 22.65%. This process aided FDH in reducing CO2 to formate, resulting in a production rate of 67.40 µmol/L/h. This research provides valuable insights for developing photo-enzyme hybrid systems that efficiently convert CO2 without the need for external electron mediators.
The high-value conversion of native lignin into functionalized aromatic compounds under visible light holds significant promise yet presents considerable challenges. In a recent study published in Angewandte Chemie International Edition, Li and colleagues developed ultrathin ZnIn2S4 microribbons using mercaptoalkanoic acid ligands, enhancing the depolymerization efficiency of lignin under visible light. This approach provides a new mechanism for converting lignin into aromatic compounds by cleaving β-O-4 bonds in natural lignin under mild conditions.
Semiconductor nanomaterials have been widely used as light-responsive photocatalysts for solar-to-fuel conversion over the past decade. However, the wide band gap of the most reported photocatalysts stems from light absorption in the visible region and results in low solar conversion efficiency. Therefore, it is necessary to develop new semiconductor nanomaterials with high absorption coefficients over the visible region as photocatalysts. The most promising candidates include Cu-based quaternary sulfide nanomaterials (CQSNs), such as Cu-II-III-S (e.g., CuZnInS, CuZnGaS), Cu-II-IV-S (e.g., Cu2ZnSnS4, Cu2ZnGeS4), and I-III-IV-S (e.g., CuInSnS4, Cu3GaSnS5). This review provides a comprehensive overview of the recent progress in developing CQSNs for various photocatalytic applications. Firstly, we present an overview of the synthesis of CQSNs with precise control over crystal phase, composition, size, and shape using solution-based methods. Then, the enhancement of photocatalytic performance was presented via the engineering of CQSNs, which included surface engineering, elemental doping, cocatalyst loading, vacancy engineering, and interface engineering. Subsequently, we further introduce the photocatalytic applications in the fields of photocatalytic and photoelectrochemical hydrogen conversion, CO2 reduction, organic synthesis, and pollutant degradation. Lastly, this review ends with views on the current challenges and opportunities of CQSNs in future studies.
With the rapid development of shipping industry, marine vessels frequently suffer from biofouling caused by marine organisms, making the effective prevention of marine biofouling a critical issue. Traditional antifouling coatings, which utilize toxic and harmful substances, pose significant risks to marine ecosystems. Therefore, the development of environmentally sustainable antifouling coatings has become imperative. Photocatalytic antifouling coatings, as an eco-friendly alternative, present a promising solution to these economic, energy, and ecological challenges. This review compares the environmental benefits of photocatalytic antifouling coatings to traditional ones, highlighting the underlying mechanisms of marine biofouling. Additionally, it explores the preparation techniques employed in photocatalytic antifoulant, analyzing the advantages, disadvantages, and potential modifications for photocatalytic coatings. Based on these insights, the future development of photocatalytic antifouling coatings is discussed, aiming to provide valuable references for the exploration of more efficient, broad-spectrum, energy-saving, environmentally friendly, and cost-effective marine antifouling technologies.
Polydopamine (PDA) is also widely sought after in photocatalytic applications due to its fascinating properties such as simple preparation, templating agent, near-infrared absorption, high photothermal conversion efficiency, abundant functional groups, and strong chelating effect of metal ions. This review will present the structural features and synthetic methods of PDA, the advantages of PDA for photocatalytic applications (templating agent effect, light absorption properties, film-forming properties, hydrophilicity, conductivity, etc.), the modulation strategies of PDA for photocatalytic applications, and the use of PDA-based photocatalytic materials for solar-powered water purification (heavy metal adsorption and reduction, catalytic degradation of organic pollutants, and antimicrobial properties), hydrogen production, hydrogen peroxide production, CO2 reduction, and organic conversion. Finally, this review will provide valuable information for the design and development of PDA-based photocatalytic materials.
Photocatalytic (PCO) and photothermocatalytic oxidation (PTCO) of ethene (C2H4) and ethanol (EtOH) are investigated using TiO2 and 1%Pt/TiO2 coating on velvet glass support in the presence of UV-A and UV-C irradiation. Both VOC are efficiently mineralised under UV-A irradiation and PCO, but the presence of Pt has a minor impact on their transformation. Instead, there is only a slight increase in the disappearance of EtOH and the formation of acetaldehyde, which are already observed in the dark. Surprisingly, when a higher photon flux is emitted with a UV-C lamp, photocatalytic disappearance and mineralisation of EtOH are less effective than under UV-A irradiation in the presence or absence of Pt. Similar behaviour is also observed on C2H4 PCO in the presence of 1%Pt/TiO2 but not on its PCO mineralisation with TiO2, which is improved by a factor equivalent to the number of photons emitted. Under PTCO, by increasing the temperature from 40 °C to 120 °C, only a benefit impact is observed on C2H4 and EtOH disappearance but an important decrease of mineralization of C2H4 was observed in presence of TiO2 and UV-C The behaviour of these two VOCs under different irradiations and temperatures will be discussed according to the catalytic process.
The direct conversion of methane into high-value chemicals has been a persistent research focus in the fields of chemical engineering and energy. Photocatalysis, as an innovative technology, not only circumvents the issues of catalyst sintering and carbon deposition associated with traditional thermal catalysis but also transcends thermodynamic limitations by providing new reaction pathways. Utilizing molecular oxygen as an oxidant generates various reactive oxygen species, offering unique thermodynamic advantages for methane conversion. This review summarizes the advancements in photocatalytic partial oxidation (PPOM) and oxidative coupling of methane (POCM) using oxygen as an oxidant. It discusses the activation mechanisms and reaction pathways of methane and oxygen in different systems, as well as the application of photochemical cycling strategies in methane conversion. Finally, it addresses the challenges in this field, proposes potential solutions, and offers perspectives on the future development of photocatalytic systems.
Our environment has been impacted by man-made pollutants mainly industries make substantial use of synthetic dyes which exhibit cytotoxicity and have significant environmental consequences. Effective photocatalyst-based approaches for degrading synthetic dyes into less toxic chemical are of great interest. Synthesizing nanoparticles (NPs) using biological approaches, particularly plant-based approaches offer advantages, decreasing the risk of NPs losing biocompatibility during synthesis, cost-effectiveness, and eco-friendliness. In this study, we employed a green synthesis method to produce manganese oxide nanoparticles (MnO NPs) utilizing leaf extract from the Lathyrus aphaca plant. The synthesized MnOx NPs were characterized through various techniques; X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), and UV–visible spectroscopy. XRD analysis showed distinct peaks, indicated the presence crystallographic planes within the MnO2 nanoparticles, thus confirming their crystalline structure. FTIR, showed the presence of the O-O stretching mode at a frequency of 719 cm−1, the presence of MnO6 oxides of manganese, and peak at 548 cm−1 corresponded to the Mn-O stretching mode. Furthermore, the green-synthesized manganese oxide nanoparticles exhibited promising photocatalytic and adsorption capabilities against Methylene Blue (MB) dye, leading to approximately 93% degradation of MB when treated with the green-synthesized MnO nanoparticles derived from plant extract. This highlights the efficacy and potential of these nanoparticles in environmental remediation applications, particularly in the degradation of methylene blue contaminants.
Photocatalytic synthesis of hydrogen peroxide (H2O2) can be an environmentally friendly and energy-saving solution. However, the oxygen reduction reaction (ORR) rate is limited due to the low solubility of O2 in water. In this study, a modified BiVO4 (BVO) photoanode combined with an Sn-coordinated phthalocyanine gas diffusion electrode (SnPc-GDE) was employed for the synthesis of H2O2, and the oxy-gen reduction reaction rate was increased through a unique three-phase interface system. When visible light was irradiated on the BVO photoanode, the hole-electron pairs were excited and the oxygen evolution reaction (OER) was driven through the holes, and the excited electrons were transferred to the SnPc-GDE to reduce O2 for the synthesis of H2O2. Oxygen vacancy enrichment on the BVO electrode was achieved by photoetching and annealing under an N2 atmosphere, which effectively improved the carrier separation efficiency. Complexation with a WO3 layer formed a built-in electric field, which further promoted the electron-hole pair separation. The SnPc catalyst-modified GDE electrode has the best selectivity for ORR and remains stable during long-term reactions. Under bias-free conditions, the generation rate of H2O2 reached 952.5 μM·L−1·h−1, with a Faradaic efficiency of 48.4%. This study provided a practical strategy for designing a highly efficient BVO/SnPc-GDE photoelectrochemical system to produce H2O2 based on improvement in electron-hole transmission efficiency and product selectivity.
Bi4V2O11 possesses a bandgap of ~1.9 eV, and the band positions of minimum conduction band and maximum valence band straddle the redox potentials of H+/H2 and O2/H2O. In the current work, photoanode made of particulate Bi4V2O11 film displays a wide range of light adsorption. However, when the anode was fabricated by drop-casting and examined for photoelectrochemical water splitting, the photocurrent density of the pristine Bi4V2O11 was low. Improvement has then been carried out by Mo-doping. The Mo-doped Bi4V2O11 photoanode achieves a maximum photocurrent density of 0.3 mA/cm2 after a post deposition necking treatment to improve the connectivity of the drop-cast particles in the film. This material also shows a stability with maintaining 80% photocurrent after 2 h test. Discussion has been made on the displayed performance in PEC water splitting of the Bi4V2O11 materials. Potential solutions have been proposed for this type of promising photoanode material for water splitting.
