Materials For Energy Conversion Research Articles

Harnessing visible light: enhancing TiO2 photocatalysis with photosensitizers for sustainable and efficient environmental solutions

The emerging field of using titanium dioxide (TiO2)-based photosensitizers for enhancing photocatalytic removal of thiazine dyes such as methylene blue (MB) from water has long been recognized for its exceptional photocatalytic properties, making it an attractive material for environmental remediation and energy conversion. However, its wide bandgap limits its responsiveness to visible light. As such, the utilization of TiO2-based photosensitizers for the removal of thiazine dyes, presents a promising avenue for diverse applications. In addressing the dual challenges of environmental pollution and harnessing sustainable energy sources, this review focuses on the removal of thiazine dyes from water and their subsequent application as photosensitizers for TiO2 materials. Thiazine dyes, ubiquitous in industrial effluents, pose environmental concerns due to their persistence and potential toxicity. Conversely, this innovative approach involves employing TiO2 materials as photocatalysts, utilizing the unique properties of thiazine dyes to enhance light absorption. Studies have shown that beyond the conventional role of thiazine dyes as colorants, they can serve as effective photosensitizers when coupled with TiO2. This tandem not only facilitates the elimination of thiazine dyes, such as MB, from water but also augments the improvement of the photocatalytic performance of TiO2 materials. The synergy between dye sensitizers and TiO2 enhances the overall efficiency of processes like dye degradation and water splitting. Dye sensitizers, acting as light energy absorbers, can efficiently transfer this energy to TiO2, thereby promoting electron transfer and generating reactive oxygen species (ROS). These ROS, in turn, initiate chemical reactions, rendering dye sensitizers valuable in applications such as wastewater treatment, solar energy conversion, and environmental remediation. As such, it is crucial to acknowledge the potential drawbacks associated with thiazine dyes, including toxicity and non-biodegradability. Consequently, careful consideration must be given to thiazine dye application and disposal. Therefore, this review manuscript delves into the comprehensive exploration of TiO2-based photosensitizers, shedding light on their efficacy in various photocatalytic processes for thiazine dye removal.

Two‐Dimensional Metallophthalocyanine Nanomaterials for Electrocatalytic Energy Conversion

Growing energy demand drives the rapid development of clean and reliable energy sources. In the past years, the exploration of novel materials with considerable efficiency and durability has drawn attention in the area of electrochemical energy conversion. Transition metal macrocyclic metallophthalocyanines (MPcs)‐based catalysts with a peculiar 2D constitution have emerged with a promising future account of their highly structural tailorability and molecular functionality which greatly extend their functionalities as electrocatalytic materials for energy conversion. This review summarizes the systematic engineering of synthesis of MPcs and their analogs in detail, and mostly pays attention to the frontier research of MPc‐based high‐performance catalysts toward different electrocatalytic processes concerning hydrogen, oxygen, water, carbon dioxide, and nitrogen, with a particular focus on discussing the interrelationship between the electrocatalytic activity and component/structure, as well as functional applications of MPcs. Finally, we give the gaps that need to be addressed after much thought.

Poly(dehydroalanine)-Based Hydrogels as Efficient Soft Matter Matrices for Light-Driven Catalysis.

Soft matter integration of photosensitizers and catalysts provides promising solutions to developing sustainable materials for energy conversion. Particularly, hydrogels bring unique benefits, such as spatial control and 3D-accessibility of molecular units, as well as recyclability. Herein, the preparation of polyampholyte hydrogels based on poly(dehydroalanine) (PDha) is reported. Chemically crosslinked PDha with bis-epoxy poly(ethylene glycol) leads to a transparent, self-supporting hydrogel. Due to the ionizable groups on PDha, this 3D polymeric matrix can be anionic, cationic, or zwitterionic depending on the pH value, and its high density of dynamic charges has a potential for electrostatic attachment of charged molecules. The integration of the cationic molecular photosensitizer [Ru(bpy)3 ]2+ (bpy = 2,2'-bipyridine) is realized, which is a reversible process controlled by pH, leading to light harvesting hydrogels. They are further combined with either a thiomolybdate catalyst ([Mo3 S13 ]2- ) for hydrogen evolution reaction (HER)or a cobalt polyoxometalate catalyst (Co4 POM = [Co4 (H2 O)2 (PW9 O34 )2 ]10- ) for oxygen evolution reaction (OER). Under the optimized condition, the resulting hydrogels show catalytic activity in both cases upon visible light irradiation. In the case of OER, higher photosensitizer stability is observed compared to homogeneous systems, as the polymer environment seems to influence decomposition pathways.

Organic Thin Films Enable Retaining the Oxidation State of Copper Catalysts during CO2 Electroreduction.

A key challenge in electrocatalysis remains controlling a catalyst's structural, chemical, and electrical properties under reaction conditions. While organic coatings showed promise for enhancing the selectivity and stability of catalysts for CO2 electroreduction (CO2RR), their impact on the chemical state of underlying metal electrodes has remained unclear. In this study, we show that organic thin films on polycrystalline copper (Cu) enable retaining Cu+ species at reducing potentials down to -1.0 V vs RHE, as evidenced by operando Raman and quasi in situ X-ray photoelectron spectroscopy. In situ electrochemical atomic force microscopy revealed the integrity of the porous organic film and nearly unaltered Cu electrode morphology. While the pristine thin film enhances the CO2-to-ethylene conversion, the addition of organic modifiers into electrolytes gives rise to improved CO2RR performance stability. Our findings showcase hybrid metal-organic systems as a versatile approach to control, beyond morphology and local environment, the oxidation states of catalysts and energy conversion materials.

Low-Dimensional Vanadium-Based High-Voltage Cathode Materials for Promising Rechargeable Alkali-Ion Batteries.

Owing to their rich structural chemistry and unique electrochemical properties, vanadium-based materials, especially the low-dimensional ones, are showing promising applications in energy storage and conversion. In this invited review, low-dimensional vanadium-based materials (including 0D, 1D, and 2D nanostructures of vanadium-containing oxides, polyanions, and mixed-polyanions) and their emerging applications in advanced alkali-metal-ion batteries (e.g., Li-ion, Na-ion, and K-ion batteries) are systematically summarized. Future development trends, challenges, solutions, and perspectives are discussed and proposed. Mechanisms and new insights are also given for the development of advanced vanadium-based materials in high-performance energy storage and conversion.

Application of graphdiyne for promote efficient photocatalytic hydrogen evolution

The photocatalytic hydrogen evolution technology converts solar energy into clean and environmentally friendly hydrogen energy, which is considered an effective means to solve environmental pollution and energy crisis. The unique sp and sp2 hybrid carbon network structure of graphdiyne endows it with excellent carrier mobility, and high porosity, making it a promising photocatalytic material for solar energy conversion. This article provides a detailed description of the unique structural properties and adjustable bandgap of graphdiyne. In addition, a detailed review was provided on the modification strategies of graphdiyne based catalysts for photocatalytic hydrogen evolution, including titanium based photocatalysts, metal oxide photocatalysts, double hydroxide catalysts, metal organic framework photocatalysts and other typical semiconductors. Finally, the challenges and opportunities for developing graphdiyne semiconductors for photocatalytic water splitting were proposed. Timely review is expected to contribute to the rapid development of graphdiyne in the field of photocatalytic hydrogen evolution.

Insights into optoelectronic behaviors of novel double halide perovskites Cs2KInX6 (X = Br, Cl, I) for energy harvesting: First principal calculation

One of the most important areas of materials science research is the creation of novel materials for energy conversion and storage. Computational simulations have become a potent tool for anticipating novel material characteristics and speeding up the discovery process in recent years. In this article, we present a computational investigation of the structural, electronic, and optical properties of double perovskites Cs2KInX6 (X = Br, Cl, and I), with a focus on their potential applications in energy conversion. The purpose of this work is to accomplish a comparative analysis of novel optoelectronic lead-free halide double perovskites. The Cs2KInX6 double perovskites compounds display direct semiconducting behavior with optical bandgap energies values of about 2.60, 3.60, and 1.67 eV for Cs2KInBr6, Cs2KInCl6, and Cs2KInI6, respectively. The results obtained underscore the remarkable characteristics of the studied compounds. Notably, a substantial absorption coefficient exceeding 106 cm−1 in the ultraviolet range and a notable absorption coefficient surpassing 105 cm−1 in the visible spectrum were observed. The obtained optoelectronic characteristics that have been indicate that Cs2KInX6 compounds hold great potential for usage in solar cell applications.

Surface Engineered Single-atom Systems for Energy Conversion.

Single-atom catalysts (SACs) are demonstrated to show exceptional reactivity and selectivity in catalytic reactions by effectively utilizing metal species, making them a favorable choice among the different active materials for energy conversion. However, SACs are still in the early stages of energy conversion, and problems like agglomeration and low energy conversion efficiency are hampering their practical applications. Substantial research focus on support modifications, which are vital for SAC reactivity and stability due to the intimate relationship between metal atoms and support. In this review, a category of supports and a variety of surface engineering strategies employed in SA systems are summarized, including surface site engineering (heteroatom doping, vacancy introducing, surface groups grafting, and coordination tunning) and surface structure engineering (size/morphology control, cocatalyst deposition, facet engineering, and crystallinity control). Also, the merits of support surface engineering in single-atom systems are systematically introduced. Highlights are the comprehensive summary and discussions on the utilization of surface-engineered SACs in diversified energy conversion applications including photocatalysis, electrocatalysis, thermocatalysis, and energy conversion devices. At the end of this review, the potential and obstacles of using surface-engineered SACs in the field of energy conversion are discussed. This review aims to guide the rational design and manipulation of SACs for target-specific applications by capitalizing on the characteristic benefits of support surface engineering.

Realization of all two-dimensional Bravais lattices with metasurface-based interference lithography

Abstract Proximity-field nanopatterning (PnP) have been used recently as a rapid, cost-effective, and large-scale fabrication method utilizing volumetric interference patterns generated by conformal phase masks. Despite the effectiveness of PnP processes, their design diversity has not been thoroughly explored. Here, we demonstrate that the possibility of generating any two-dimensional lattice with diverse motifs. By controlling the amplitude, phase, and polarization of each diffraction beam, we can implement all two-dimensional Bravais lattices in three-dimensional space. The results may provide diverse applications that require three-dimensional nanostructures from optical materials and structural materials to energy storage or conversion materials.

Recent Progress in the Application of Ion Beam Technology in the Modification and Fabrication of Nanostructured Energy Materials.

The development of green, renewable energy conversion and storage systems is an urgent task to address the energy crisis and environmental issues in the future. To achieve high performance, stable, and safe operation of energy conversion and storage systems, energy materials need to be modified and fabricated through rationalization. Among various modification and fabrication strategies, ion beam technology has been widely used to introduce various defects/dopants into energy materials and fabricate various nanostructures, where the structure, composition, and property of prefabricated materials can be further accurately tailored to achieve better performance. In this paper, we review the recent progress in the application of ion beam technology in material modification and fabrication, focusing on nanostructured energy materials for energy conversion and storage including photo- (electro-) water splitting, batteries (solar cells, fuel cells, and metal-ion batteries), supercapacitors, thermoelectrics, and hydrogen storage. This review first provides a brief basic overview of ion beam technology and describes the classification and technological advantages of ion beam technology in the modification and fabrication of materials. Then, modification of energy materials by ion beams is reviewed mainly concerning doping and defect introduction. Fabrication of energy materials is also discussed mainly in terms of heterojunctions, nanoparticles, nanocavities, and other nanostructures. In particular, we emphasize the advantages of ion beam technology in improving the performance of energy materials. Finally, we point out our understanding of challenges and future perspectives in applying ion beam technology for the modification and fabrication of energy materials.

Structure-based screening of sp2 hybridized small donor bridges as donor: acceptor switches for optical and photovoltaic applications: DFT way.

This research aims to investigate the potential of pyrazine-based small donor moieties as donor-acceptor switches for optical and photovoltaic applications. The designed organic dyes have a high light harvesting efficiency (LHE) and can potentially generate significant electrical energy. The study focuses on understanding the structural and electronic properties of these dyes through the analysis of dihedral angles, bond lengths, and energies of frontier molecular orbitals The UV-Vis spectroscopy parameters of the designed organic dyes revealed their absorption characteristics, including transition energies, wavelengths (λmax), and oscillator strengths (f). The photovoltaic properties of the developed organic dyes show a range of values: a range of 0.95-0.99 for LHE and a range of 1.77-33.02 W for maximum power output (Pmax) with the highest value for dye DDP5. For their stabilization energies, their natural bond orbitals had values ranging from 0.56 to 128.48kcal/mol, their E(j)E(i) values from 0.22 to 1.29 a.u, and their Fi,j values from 0.024 to 0.213kcal/mol. Out of all dyes, the DDP5 produced highest push-pull effect and can be good choice for further studies. The design of these novel organic materials for effective and economical solar energy conversion will be aided by evaluating the potential of 5,10-diphenyl-5,10-dihydrophenazine as a donor moiety and determining the structure-property correlations controlling the photovoltaic performance of the compounds.

Novel graphene-like layer-by-layer stacked carbon nanotube-supported Fe-Ni alloy for oxygen evolution and oxygen reduction reactions

In this study, we prepared a novel graphene-like stacked carbon nanotube-supported Fe-Ni alloy nanometer composite material. The cubic structure of nickel dimethylglyoxime was synthesized as the base material. Under hydrothermal condition, FePc was adsorbed on the surface of the nickel dimethylglyoxime cube. In addition, hydrogen peroxide not only decomposes FePc into Pc and Fe2+, but also reduces Fe2+ to Fe. On the other hand, hydrogen peroxide was first found could decompose and peel the cube of nickel dimethylglyoxime into a novel type of nanotubes with graphene-like nanosheet stacking structure. After the final calcination, the Fe2+ and Ni2+ were converted to FeNi alloy, and the dimethylglyoxime carrier with its loaded Pc was converted to carbon material. The novel structure has a large BET, which is conducive to electron transport, product transport and provides a large active site for Fe-Ni3 alloy. The composite has high electro-catalysis performance for OER and ORR, which provides a new idea for the study of new energy reserves, energy conversion and reserve materials. This study provides a new idea for preparing novel carbon nanotube-loaded transition metal composites in the field of electrocatalysis.

Porous Flower-Like Nanoarchitectures Derived from Nickel Phosphide Nanocrystals Anchored on Amorphous Vanadium Phosphate Nanosheet Nanohybrids for Superior Overall Water Splitting.

Transition metal phosphides (TMPs) and phosphates (TM-Pis) nanostructures are promising functional materials for energy storage and conversion. Nonetheless, controllable synthesis of crystalline/amorphous heterogeneous TMPs/TM-Pis nanohybrids or related nanoarchitectures remains challenging, and their electrocatalytic applications toward overall water splitting (OWS) are not fully explored. Herein, the Ni2P nanocrystals anchored on amorphous V-Pi nanosheet based porous flower-like nanohybrid architectures that are self-supported on carbon cloth (CC) substrate (Ni2P/V-Pi/CC) are fabricated by conformal oxidation and phosphorization of pre-synthesized NiV-LDH/CC. Due to the unique microstructures and strong synergistic effects of crystalline Ni2P and amorphous V-Pi components, the obtained Ni2P/V-Pi/CC owns abundant active sites, suitable surface/interface electronic structure and optimized adsorption-desorption of reaction intermediates, resulting in outstanding electrocatalytic performances toward hydrogen and oxygen evolution reactions in alkaline media. Correspondingly, the assembled Ni2P/V-Pi/CC||Ni2P/V-Pi/CC electrolyzer only needs an ultralow cell voltage (1.44V) to deliver 10mA cm-2 water-splitting currents, exceeding its counterparts, recently reported bifunctional catalysts-based devices, and Pt/C/CC||IrO2/CC pairs. Moreover, the Ni2P/V-Pi/CC||Ni2P/V-Pi/CC manifests remarkable stability. Also, such device shows a certain prospect for OWS in acidic media. This work may spur the development of TMPs/TMPis-based nanohybrid architectures by combining structure and phase engineering, and push their applications in OWS or other clean energy options.

Enhanced oxygen evolution reaction activity on two-dimensional vdW ferromagnetic Cr2Ge2Te6 through synergism between two active sites.

To design an efficient, low-cost, and easily recoverable oxygen evolution reaction (OER) electrocatalyst, this work focuses on two-dimensional vdW ferromagnetic Cr2Ge2Te6. Based on the density functional theory (DFT) calculations, the adsorption of oxygen-containing intermediates during the OER process will gradually decrease the bandgap of Cr2Ge2Te6, thus increasing its electrical conductivity. More importantly, we propose a two active sites synergistic mechanism through a hydroxyl-boosted pathway. With the combined action of the two active sites, the binding between the oxygen-containing intermediates and the surfaces is enhanced. The enhancement comes from dramatic charge-transfer-induced Te-3p and O-2p orbital enhancement. As a result, the overpotential of the OER reduces from 1.25 to 0.59 V. We hope these findings will pave the way for more experimental and theoretical research to explore the potential applications of two-dimensional vdW ferromagnetic materials in energy storage and conversion.

Selective activation of MoS2 grain boundaries for enhanced electrochemical activity.

Molybdenum disulfide (MoS2) has emerged as a promising material for catalysis and sustainable energy conversion. However, the inertness of its basal plane to electrochemical reactions poses challenges to the utilization of wafer-scale MoS2 in electrocatalysis. To overcome this limitation, we present a technique that enhances the catalytic activity of continuous MoS2 by preferentially activating its buried grain boundaries (GBs). Through mild UV irradiation, a significant enhancement in GB activity was observed that approaches the values for MoS2 edges, as confirmed by a site-selective photo-deposition technique and micro-electrochemical hydrogen evolution reaction (HER) measurements. Combined spectroscopic characterization and ab-initio simulation demonstrates substitutional oxygen functionalization at the grain boundaries to be the origin of this selective catalytic enhancement by an order of magnitude. Our approach not only improves the density of active sites in MoS2 catalytic processes but yields a new photocatalytic conversion process. By exploiting the difference in electronic structure between activated GBs and the basal plane, homo-compositional junctions were realized that improve the photocatalytic synthesis of hydrogen by 47% and achieve performances beyond the capabilities of other catalytic sites.

Biomass‐Derived Electrocatalysts: Low‐Cost, Robust Materials for Sustainable Electrochemical Energy Conversion

Biomass‐Derived Electrocatalysts: Low‐Cost, Robust Materials for Sustainable Electrochemical Energy Conversion

Recent advances of metal active sites in photocatalytic CO2 reduction.

Photocatalytic CO2 reduction captures solar energy to convert CO2 into hydrocarbon fuels, thus shifting the dependence on rapidly depleting fossil fuels. Among the various proposed photocatalysts, systems containing metal active sites (MASs) possess obvious advantages, such as effective photogenerated carrier separation, suitable adsorption and activation of intermediates, and achievable C-C coupling to generate multi-carbon (C2+) products. The present review aims to summarize the typical photocatalytic materials with MAS, highlighting the critical role of different formulations of MAS in CO2 photoreduction, especially for C2+ product generation. State-of-the-art progress in the characterization and theoretical calculations for MAS-containing photocatalysts is also emphasized. Finally, the challenges and prospects of catalytic systems involving MAS for solar-driven CO2 conversion are outlined, providing inspiration for the future design of materials for efficient photocatalytic energy conversion.

Immobilization of metal active centers in reticular framework materials for photocatalytic energy conversion

To enhance the economy and society's sustainability, prioritizing innovative, green energy conversion methods is essential.

Hydrous ruthenium oxide triggers template-free and spontaneous growth of metal nanostructures.

Intrinsically conductive ruthenium oxide is an excellent material for energy storage and conversion. Herein, we present hydrous RuO2 (H-RuO2) as a potent reducing agent to achieve spontaneous growth of multiple noble metals at room temperature. Self-assembled gold and platinum, comprising small-sized nanoparticles, are generated on the surface of H-RuO2 without the need for additional templates. Structural analysis reveals that the disordered structure and the presence of oxygen vacancies trigger interfacial redox reactions between H-RuO2 and oxidative metal salts. The resulting integrated nanostructures, consisting of a metal oxide and different metals (H-RuO2@metal), are subsequently used to treat inflammatory bowel diseases. In addition to biomedical applications, our developed synthetic strategy, using reactive oxides to spontaneously generate multicomponent nanostructures, also holds great significance for other catalysis-based applications.

Polyimide covalent organic frameworks bearing star-shaped electron-deficient polycyclic aromatic hydrocarbon building blocks: molecular innovations for energy conversion and storage.

Polyimide covalent organic frameworks (PI-COFs) are outstanding functional materials for electrochemical energy conversion and storage owing to their integrated advantages of the high electroactive feature of polyimides and the periodic porous structure of COFs. Nevertheless, only anhydride monomers with C2 symmetry are generally used, and limited selectivity of electron-deficient monomers has become a major obstacle in the development of materials. The introduction of polycyclic aromatic hydrocarbons (PAHs) is a very effective method to regulate the structure-activity relationship of PI-COFs due to their excellent stability and electrical properties. Over the past two years, various star-shaped electron-deficient PAH building blocks possessing different compositions and topologies have been successfully fabricated, greatly improving the monomer selectivity and electrochemical performances of PI-COFs. This paper systematically summarizes the recent highlights in PI-COFs based on these building blocks. Firstly, the preparation of anhydride (or phthalic acid) monomers and PI-COFs related to different star-shaped PAHs is presented. Secondly, the applications of these PI-COFs in energy conversion and storage and the corresponding factors influencing their performance are discussed in detail. Finally, the future development of this meaningful field is briefly proposed.