S-Scheme ZIF-67/CuFe-LDH Heterojunction for High-Performance Photocatalytic H2 Evolution and CO2 to MeOH Production

CuCo2S4/g-C3N4-x S-Scheme Heterojunction for Photothermal-Assisted Photocatalytic CO2 Reduction

Photocatalytic conversion of CO2 into chemical fuels has emerged as a research hotspot, aiming to mitigate the rapid depletion of fossil fuels and alleviate global warming. However, the inherent low carrier separation efficiency and limited solar light utilization of photocatalysts lead to unsatisfactory CO2 conversion efficiency. In this study, an appealing CuCo2S4/g-C3N4-x S-scheme heterostructure is successfully fabricated by a simple polyol reflux method. Notably, nitrogen vacancies enhance the Fermi level difference between CuCo2S4 and g-C3N4-x, resulting in a stronger interfacial built-in electric field. The full-spectrum strong optical absorption capability endows the synthesized catalysts with superior light-harvesting property. The photothermal effect-induced temperature increase accelerates the cyclic process of CO2 adsorption and CO desorption on the catalyst surface. Most importantly, the S-scheme charge transfer pathway ensures the efficient separation of photogenerated carriers. Thanks to these synergistic benefits, CuCo2S4/g-C3N4-x exhibits exceptional photothermal-assisted photocatalytic CO2 reduction performance. Under simulated sunlight, the average CO production rate of CuCo2S4/g-C3N4-x reaches 24.64 μmol g-1 h-1, which is 12.1 and 27.1 times higher than that of g-C3N4 and CuCo2S4, respectively. This study offers a novel strategy for designing photocatalysts with outstanding CO2 conversion performance.

Engineering S-Scheme Heterojunction via MOF-on-MOF for Photocatalytic Nitroarene Hydrogenation

Photocatalytic nitroarene reduction provides a promising strategy for the sustainable production of aniline. The construction of S-scheme heterostructures with a clear interfacial charge transfer mechanism is considered as an effective strategy to improve the photocatalytic performance of photocatalysts. The assembly of MOF-on-MOF might be used to construct S-scheme heterojunctions due to the rich structures, effective charge transport channels, and fast mass transfer of MOFs. Herein, 2D Pd-PPF-1 was coated on 3D Pd-PCN-222 through a presurface modification strategy, and the prepared Pd-PPF-1/Pd-PCN-222 with an S-scheme heterojunction displayed the morphology of a 2D nanoflower winding around a 3D rod. As for photocatalytic nitroarene hydrogenation, the as-obtained Pd-PPF-1/Pd-PCN-222 catalyst exhibited much higher photocatalytic performance than Pd-PPF-1, Pd-PCN-222, or a physical mixture of Pd-PPF-1 and Pd-PCN-222. The high catalytic performance of Pd-PPF-1/Pd-PCN-222 might be attributed to the formation of the S-scheme heterojunction, which not only retained the redox capability of the parent MOFs but also separated photogenerated carriers. This work presents a constructive route for designing 2D-on-3D MOF S-scheme heterojunction with controllable morphology and high photocatalytic ability.

Combat against antibiotic resistance genes during photo-treatment of magnetic Zr-MOFs@Layered double hydroxide heterojunction: Conjugative transfer risk mitigating and bacterial inactivation

The dissemination of antimicrobial resistance (AMR) in wastewater treatment poses a severe threat to the global ecological environment. This study explored the effectiveness of photocatalysis in inactivating antibiotic resistant bacteria (ARB) and quantitatively clarified the inhibiting rate of the transfer of antibiotics resistance genes (ARGs). Herein, the magnetic heterojunction as UiO-66-NH2@CuFe LDH-Fe3O4 (UN-66@LDH-Fe) effectively facilitated the electron-hole separation and accelerated the photogenerated charge transfer, thereby guaranteeing the stable practical application in aeration tanks. Notably, the internal electric field of heterogeneous photocatalyst resulted in significant increase of ARGs inactivation, achieving 5.63 log of ARB, 3.66 log of tetA and 3.57 log of Ampr genes were photodegraded under optimal reaction conditions within 6 h. Based on the complex microbial and molecular mechanism of multiple-ARB communities inactivation in photo-treatment, the photogenerated reactive oxygen species (ROSs, ·OH and ·O2-) effectively destroyed bacterial membrane protein, thereby the intracellular ROSs and redox cycles further induced oxidative stress, attributing to the abundance reduction of ARGs and their host bacteria. Moreover, long-term (7 days) continuous operation preliminarily verified the practical potential in reducing AMR spread and developing wastewater treatment efficacy. Overall, this study presented an advantageous synergistic strategy for mitigating the AMR-associated environmental risk in wastewater treatment.

Charge-transfer dynamics in S-scheme photocatalyst

Natural photosynthesis represents the pinnacle that green chemistry aims to achieve. Photocatalysis, inspired by natural photosynthesis and dating back to 1911, has been revitalized, offering promising solutions to critical energy and environmental challenges facing society today. As such, it represents an important research avenue in contemporary chemical science. However, single photocatalytic materials often suffer from the rapid recombination of photogenerated electrons and holes, resulting in poor performance. S-scheme heterojunctions have emerged as a general method to enhance charge transfer and separation, thereby greatly improving photocatalytic efficiencies. This Perspective delves into the electron transfer dynamics in S-scheme heterojunctions, providing a comprehensive overview of their development and key characterization techniques, such as femtosecond transient absorption spectroscopy, in situ irradiated X-ray photoelectron spectroscopy and Kelvin probe force microscopy. By addressing a critical research gap, this work aims to trigger further understanding and advances in photo-induced charge-transfer processes, thereby contributing to green chemistry and the United Nations sustainable development goals.

Emerging ZnO Semiconductors for Photocatalytic CO2 Reduction to Methanol

Carbon recycling is poised to emerge as a prominent trend for mitigating severe climate change and meeting the rising demand for energy. Converting carbon dioxide (CO2) into green energy and valuable feedstocks through photocatalytic CO2 reduction (PCCR) offers a promising solution to global warming and energy needs. Among all semiconductors, zinc oxide (ZnO) has garnered considerable interest due to its ecofriendly nature, biocompatibility, abundance, exceptional semiconducting and optical properties, cost-effectiveness, easy synthesis, and durability. This review thoroughly discusses recent advances in mechanistic insights, fundamental principles, experimental parameters, and modulation of ZnO catalysts for direct PCCR to C1 products (methanol). Various ZnO modification techniques are explored, including atomic size regulation, synthesis strategies, morphology manipulation, doping with cocatalysts, defect engineering, incorporation of plasmonic metals, and single atom modulation to boost its photocatalytic performance. Additionally, the review highlights the importance of photoreactor design, reactor types, geometries, operating modes, and phases. Future research endeavors should prioritize the development of cost-effective catalyst immobilization methods for solid-liquid separation and catalyst recycling, while emphasizing the use of abundant and non-toxic materials to ensure environmental sustainability and economic viability. Finally, the review outlines key challenges and proposes novel directions for further enhancing ZnO-based photocatalytic CO2 conversion processes.

Atomically Tailored Zn-ZIF-8 via RuNi Nanoalloy Replacement for Improved Photocatalytic H2 Evolution

In this study, we developed a solid-state atomic replacement method for metal catalysts, enabling the exchange of metal atoms between single atoms and nanoalloys to create new combinations of nanoalloys and single atoms. We observed that partial metal interchange occurred between the RuNi nanoalloy and Zn from the zeolitic imidazolate framework-8 (ZIF-8) on a carbon-nitrogen framework (CNF) at a high temperature of 900 °C, leading to the creation of RuZn nanoparticles and single nickel atoms (Ni-CN). Extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) analyses revealed that Ni is atomically dispersed within (RuZn)/Ni-CN. This finding confirms the migration of Zn and Ni during the pyrolysis of the RuNi@ZIF-8 precursor, providing definitive evidence of atomic replacement. Due to the synergistic influence of RuZn nanocrystals and Ni-CN, the resulting (RuZn)/Ni-CN multisite catalyst exhibited superior hydrogen evolution reaction (HER) ability compared to the conventional nanoalloy-based catalysts. Density functional theory calculations revealed that the integration of the (RuZn)n cluster on Ni surrounded with different N-coordinated carbon structures enhanced HER activity with the optimized (RuZn)n/NiN2C2 catalyst exhibiting a low ΔGH and improved electron charge redistribution, thereby promoting favorable hydrogen adsorption. Our findings provide valuable insights into the design and optimization of photocatalysts through atomic-level engineering, opening new avenues for efficient and sustainable energy conversion technologies.

Sputtering thin films: Materials, applications, challenges and future directions

Sputtering is an effective technique for producing ultrathin films with diverse applications. The review begins by providing an in-depth overview of the background, introducing the early development of sputtering and its principles. Consequently, progress in advancements made in recent decades highlights the renaissance of sputtering as a powerful technology for creating thin films with varied compositions, structures, and properties. For the first time, we have discussed a thorough overview of several sputtered thin film materials based on metal and metal oxide, metal nitride, alloys, carbon, and ceramic-based thin film along with their properties and their applicability in various fields. We further delve into the applications of sputter-coated thin films, specifically emphasizing their relevance in environmental sustainability, energy and electronics, and biomedical fields. We critically examine the recent advancements in developing sputter-coated catalysts for eliminating water pollutants andhydrogen generation. Additionally, the review sheds light on advantages, shortcomings, and future directions for developing sputter-coated thin films utilized in biodegradable metals and alloys with enhanced corrosion resistance and biocompatibility. This review is a comprehensive integration of recent literature, covering diverse sputtering thin film applications. We delve deeply into various material types and emphasize critical analysis of recent advancements, particularly in environmental, energy, and biomedical fields. By offering insights into both advancements and limitations, the review provides a nuanced understanding essential for practical utilization.

Visible-Light-Driven Photocatalytic H2 Production Using Composites of Co-Al Layered Double Hydroxides and Graphene Derivatives

The direct conversion of solar energy into chemical energy represents an enormous challenge for current science. One of the commonly proposed photocatalytic systems is composed of a photosensitizer (PS) and a catalyst, together with a sacrificial electron donor (ED) when only the reduction of protons to H2 is addressed. Layered double hydroxides (LDH) have emerged as effective catalysts. Herein, two Co-Al LDH and their composites with graphene oxide (GO) or graphene quantum dots (GQD) have been prepared by coprecipitation and urea hydrolysis, which determined their structure and so their catalytic performance, giving H2 productions between 1409 and 8643 μmol g-1 using a ruthenium complex as PS and triethanolamine as ED at 450 nm. The influence of different factors, including the integration of both components, on their catalytic behavior, has been studied. The proper arrangement between the particles of both components seems to be the determining factor for achieving a synergistic interaction between LDH and GO or GQD. The novel Co-Al LDH composite with intercalated GQD achieved an outstanding catalytic efficiency (8643 μmol H2 g-1) and exhibited excellent reusability after 3 reaction cycles, thus representing an optimal integration between graphene materials and Co-Al LDH for visible light driven H2 photocatalytic production.

Hybridization of layered double hydroxides with functional particles

Layered double hydroxides (LDHs) are a class of materials with useful properties associated with their anion exchange abilities as well as redox and adsorptive properties for a wide range of applications including adsorbents, catalysts and their supports, electrodes, pigments, ceramic precursors, and drug carriers. In order to satisfy the requirements for each application as well as to find alternative applications, the preparation of LDHs with the desired composition and particle morphology and post-synthetic modification by the host-guest interactions have been examined. In addition, the hybridization of LDHs with various functional particles has been reported to design materials of modified, improved, and multiple functions. In the present article, the preparation, the heterostructure and the application of hybrids containing LDHs as the main component are overviewed.

A comprehensive review on the application of semiconducting materials in the degradation of effluents and water splitting

In this comprehensive review article, we delve into the critical intersection of environmental science and materials science. The introduction sets the stage by emphasizing the global water shortage crisis and the dire consequences of untreated effluents on ecosystems and human health. As we progress into the second section, we embark on an intricate exploration of piezoelectric and photocatalytic principles, illuminating their significance in wastewater treatment and sustainable energy production. The heart of our review is dedicated to a detailed analysis of the detrimental impacts of effluents on human health, underscoring the urgency of effective treatment methods. We dissected three key materials in the realm of piezo-photocatalysis: ZnO-based materials, BaTiO3-based materials, and bismuth-doped materials. Each material is scrutinized for its unique properties and applications in the removal of pollutants from wastewater, offering a comprehensive understanding of their potential to address this critical issue. Furthermore, our exploration extends to the realm of hydrogen production, where we discuss various types of hydrogen and the role of piezo-photocatalysis in generating clean and sustainable hydrogen. By illuminating the synergistic potential of these advanced materials and technologies, we pave the way for innovative solutions to the pressing challenges of water pollution and renewable energy production. This review article not only serves as a valuable resource for researchers and scholars in the fields of material science and environmental engineering but also underscores the pivotal role of interdisciplinary approaches in addressing complex global issues.