Materials For Energy Conversion Research Articles

Porosity Tunable Metal-Organic Framework (MOF)-Based Composites for Energy Storage Applications: Recent Progress

To solve the energy crisis and environmental issues, it is essential to create effective and sustainable energy conversion and storage technologies. Traditional materials for energy conversion and storage however have several drawbacks, such as poor energy density and inadequate efficiency. The advantages of MOF-based materials, such as pristine MOFs, also known as porous coordination polymers, MOF composites, and their derivatives, over traditional materials, have been thoroughly investigated. These advantages stem from their high specific surface area, highly adjustable structure, and multifunctional nature. MOFs are promising porous materials for energy storage and conversion technologies, according to research on their many applications. Moreover, MOFs have served as sacrificial materials for the synthesis of different nanostructures for energy applications and as support substrates for metals, metal oxides, semiconductors, and complexes. One of the most intriguing characteristics of MOFs is their porosity, which permits space on the micro- and meso-scales, revealing and limiting their functions. The main goals of MOF research are to create high-porosity MOFs and develop more efficient activation techniques to preserve and access their pore space. This paper examines the porosity tunable mixed and hybrid MOF, pore architecture, physical and chemical properties of tunable MOF, pore conditions, market size of MOF, and the latest development of MOFs as precursors for the synthesis of different nanostructures and their potential uses.

Albizia Procera-Derived Nitrogen-Doped Carbon: A Versatile Material for Energy Conversion, Storage, and Environmental Applications.

This review explores the diverse applications of nitrogen-doped carbon derived from Albizia procera, known as white siris. Native to the Indian subcontinent and tropical Asia, this species thrives in varied conditions, contributing to sustainable development. The nitrogen-rich leaves of Albizia procera are an excellent source for synthesizing nitrogen-doped carbon, which possesses remarkable properties for advanced technologies. This material demonstrates significant potential in energy conversion and storage systems, such as supercapacitors and batteries, due to its high surface area, electrical conductivity, and chemical stability. Nitrogen doping introduces active sites that enhance charge storage, making it ideal for renewable energy applications. Additionally, this material shows promise in environmental processes like water splitting and carbon dioxide capture, where its porous structure and chemical functionality enable efficient adsorption and remediation. The review discusses synthesis methodologies, including pyrolysis and activation, to optimize its properties for energy and environmental uses. Nitrogen-doped carbon derived from Albizia procera may expand into catalytic applications, enhancing its role in sustainable technologies. This review underscores the importance of utilizing natural resources like Albizia procera to develop materials that drive both environmental sustainability and technological innovation.

Advancements in MoS2‒based Anodes for Li-Ion Batteries: Recent Progress, Challenges, and Future Directions

Significant progress has recently been made in the development of new materials for energy storage and conversion. One of the commercially dominant energy storage technologies is lithium-ion batteries (LIBs), which...

High-entropy oxides: Emergent materials for electrochemical energy storage and conversion

High-entropy oxides: Emergent materials for electrochemical energy storage and conversion

Dual back interface engineering optimized charge carrier dynamics in Sb2(S,Se)3 photocathodes for efficient solar hydrogen production.

Antimony sulfoselenide (Sb2(S,Se)3) is a promising sunlight absorber material for solar energy conversion in photovoltaic (PV) cells and photoelectrochemical (PEC) photoelectrodes due to its excellent photoelectric properties. However, the obtained thin-film and back contact properties significantly influence the PEC performance of photocathodes, causing severe bulk recombination, carrier transport loss, and deteriorating half-cell solar-to-hydrogen (HC-STH) efficiency. This study introduces an intriguing dual back interface engineering strategy for Sb2(S,Se)3 photocathodes by incorporating an intermediate MoO2 layer and a secondary carrier transport channel of Au to strengthen charge carrier dynamics. The synergistic assembly of these dual back interface layers improves the growth kinetics and achieves the optimal orientation of Sb2(S,Se)3 thin films by increasing substrate wettability. Moreover, by shortening the back contact barrier height and passivating defect-assisted recombinations, these dual back underlayers simultaneously enhance carrier transport and separation efficiencies. As a result, the photocurrent density of the champion Sb2(S,Se)3 photocathode increases from 5.89 to 32.60 mA cm-2, and the HC-STH conversion efficiency improves significantly from 0.30% to 3.58%, representing the highest value for Sb2(S,Se)3-based photocathodes. This work highlights the effectiveness of dual back interface engineering in promoting the PEC performance of chalcogenide photocathodes for solar hydrogen evolution applications.

Advanced high-entropy materials for high-quality energy storage and conversion

Advanced high-entropy materials for high-quality energy storage and conversion

Neutron scattering studies of complex lattice dynamics in energy materials

Lattice dynamics play a crucial role in understanding the physical mechanisms of cutting-edge energy materials. Many excellent energy materials have complex multiple-sublattice structures, and their lattice dynamics are intricate and the underlying mechanisms are difficult to understand. Neutron scattering technologies, known for their high energy and momentum resolution, are powerful tools for simultaneously characterizing material structure and complex lattice dynamics. In recent years, neutron scattering techniques have significantly contributed to the study of energy materials, shedding light on their physical mechanisms. Starting from the basic properties of neutrons and double differential scattering cross sections, this paper introduces in detail the working principles, spectrometer structures, and comparisons with other technologies of several neutron scattering techniques commonly used in energy material research, including neutron diffraction and neutron total scattering to characterize material structure, quasi-elastic neutron scattering and inelastic neutron scattering to characterize lattice dynamics. Then, this article showcases significant research advancements in the field of energy materials utilizing neutron scattering as a primary characterization method:<br>1. In the case of Ag<sub>8</sub>SnSe<sub>6</sub> superionic thermoelectric materials, single crystal inelastic neutron scattering experiments debunk the "liquid-like phonon model" as the primary contributor to ultra-low lattice thermal conductivity. Instead, extreme phonon anharmonic scattering is identified as the key factor based on the special temperature dependence of phonon linewidth.<br>2. Analysis of quasi-elastic and inelastic neutron scattering spectra reveals changes in the correlation between framework and Ag<sup>+</sup> sublattices during the superionic phase transition of Ag<sub>8</sub>SnSe<sub>6</sub> compounds. Further investigations using neutron diffraction and molecular dynamics simulations unveil a new superionic phase transition and ion diffusion mechanism, primarily governed by weakly bonded Se atoms.<br>3. Research on NH<sub>4</sub>I compounds demonstrates a strong coupling between molecular orientation rotation and lattice vibration, and the strengthening of phonon anharmonicity with temperature can decouple this interaction and induce plastic phase transition. This phenomenon results in a significant configuration entropy change, showing potential applications in barocaloric refrigeration.<br>4. In the CsPbBr<sub>3</sub> perovskite photovoltaic materials, inelastic neutron scattering uncovers low-energy phonon damping of the [PbBr<sub>6</sub>] sublattice, influencing electron-phonon coupling and the band edge electronic state. This special anharmonic vibration of the [PbBr<sub>6</sub>] sublattice prolongs the lifetime of hot carriers, impacting the material's electronic properties.<br>5. In MnCoGe magnetic refrigeration materials, in-situ neutron diffraction experiments highlight the role of valence electron transfer between sublattices in altering crystal structural stability and magnetic interactions. This process triggers a transformation from a ferromagnetic to an incommensurate spiral antiferromagnetic structure, expanding our understanding of magnetic phase transition regulation.<br>These examples underscore the interconnected nature of lattice dynamics with other degrees of freedom, such as sublattices, charge, and spin, in energy conversion and storage materials. Through these typical examples, this article aims to provide a reference for further exploration and understanding of energy materials and lattice dynamics.

Advancements in Ge-based thermoelectric materials for efficient waste heat energy conversion: a comprehensive review

Abstract Thermoelectric materials hold significant promise for converting waste heat energy into electrical energy. The performance of these materials and devices is assessed using a quantitative measure known as the figure of merit, which relies on the Seebeck coefficient, thermal conductivity, and electrical conductivity of the material. Different classes of thermoelectric materials have their own merits and demerits. High temperature thermoelectric materials are useful for space exploration, automobile applications, etc Many materials have been explored within temperature range of 300–900 K, showing suitable properties for thermoelectric applications. Germanium, an inorganic material is investigated in details, due to its high Seebeck coefficient and better thermal stability. Silicon-Germanium alloys are thermoelectric materials suitable for operating at high temperatures. These materials help in reduction of emission of green house gases. Extensive efforts have been devoted to enhance the efficiency of Germanium-based thermoelectric materials and devices through various techniques such as doping, nanostructuring, electron energy filtering, and band engineering. Recently, a new material Ge0.94Sm0.06Te has been introduced, reporting a high figure of merit value of 2.5 at 730 K. Many theoretical studies are also reported showing the potential of new Germanium-based thermoelectric materials. Further, 2D Germanium-based materials show enhanced thermoelectric properties as well. These findings underscore the significance of Germanium as a thermoelectric material. This review provides an overview of the latest developments in Germanium-based thermoelectric materials and focuses on different strategies to enhance their thermoelectric performance. Additionally, the suitability of various Germanium-based thermoelectric materials in comparison to other materials for energy harvesting applications is extensively discussed in this review.

Participation of Polymer Materials in the Structure of Piezoelectric Composites.

This review explores the integration of polymer materials into piezoelectric composite structures, focusing on their application in sensor technologies, and wearable electronics. Piezoelectric composites combining ceramic phases like BaTiO3, KNN, or PZT with polymers such as PVDF exhibit significant potential due to their enhanced flexibility, processability, and electrical performance. The synergy between the high piezoelectric sensitivity of ceramics and the mechanical flexibility of polymers enables the development of advanced materials for biomedical devices, energy conversion, and smart infrastructure applications. This review discusses the evolution of lead-free ceramics, the challenges in improving polymer-ceramic interfaces, and innovations like 3D printing and surface functionalization, which enhance charge transfer and material durability. It also covers the effects of radiation on these materials, particularly in nuclear applications, and strategies to enhance radiation resistance. The review concludes that polymer materials play a critical role in advancing piezoelectric composite technologies by addressing environmental and functional challenges, paving the way for future innovations.

Concurrently Boosting Activity and Stability of Oxygen Reduction Reaction Catalysts via Judiciously Crafting Fe–Mn Dual Atoms for Fuel Cells

The ability to unlock the interplay between the activity and stability of oxygen reduction reaction (ORR) represents an important endeavor toward creating robust ORR catalysts for efficient fuel cells. Herein, we report an effective strategy to concurrent enhance the activity and stability of ORR catalysts via constructing atomically dispersed Fe-Mn dual-metal sites on N-doped carbon (denoted (FeMn-DA)-N-C) for both anion-exchange membrane fuel cells (AEMFC) and proton exchange membrane fuel cells (PEMFC). The (FeMn-DA)-N-C catalysts possess ample dual-metal atoms consisting of adjacent Fe-N4 and Mn-N4 sites on the carbon surface, yielded via a facile doping-adsorption-pyrolysis route. The introduction of Mn carries several advantageous attributes: increasing the number of active sites, effectively anchoring Fe due to effective electron transfer to Mn (revealed by X-ray absorption spectroscopy and density-functional theory (DFT), thus preventing the aggregation of Fe), and effectively circumventing the occurrence of Fenton reaction, thus reducing the consumption of Fe. The (FeMn-DA)-N-C catalysts showcase half-wave potentials of 0.92 and 0.82V in 0.1M KOH and 0.1M HClO4, respectively, as well as outstanding stability. As manifested by DFT calculations, the introduction of Mn affects the electronic structure of Fe, down-shifts the d-band Fe active center, accelerates the desorption of OH groups, and creates higher limiting potentials. The AEMFC and PEMFC with (FeMn-DA)-N-C as the cathode catalyst display high power densities of 1060 and 746mWcm-2, respectively, underscoring their promising potential for practical applications. Our study highlights the robustness of designing Fe-containing dual-atom ORR catalysts to promote both activity and stability for energy conversion and storage materials and devices.

High-Entropy Oxides: Pioneering the Future of Multifunctional Materials.

The high-entropy concept affords an effective method to design and construct customized materials with desired characteristics for specific applications. Extending this concept to metal oxides, high-entropy oxides (HEOs) can be fabricated, and the synergistic elemental interactions result in the four core effects, i.e., the high-entropy effect, sluggish-diffusion effect, severe-lattice-distortion effect, and cocktail effect. All these effects greatly enhance the functionalities of this vast material family, surpassing conventional low- and medium-entropy metal oxides. For instance, the high phase stability, excellent electrochemical performance, and fast ionic conductivity make HEOs one of the hot next-generation candidate materials for electrochemical energy conversion and storage devices. Significantly, the extraordinary mechanical, electrical, optical, thermal, and magnetic properties of HEOs are very attractive for applications beyond catalysts and batteries, such as electronic devices, optic equipment, and thermal barrier coatings. This review will overview the entropy-stabilized composition and structure of HEOs, followed by a comprehensive introduction to the electrical, optical, thermal, and magnetic properties. Then, several typical applications, i.e., transistor, memristor, artificial synapse, transparent glass, photodetector, light absorber and emitter, thermal barrier coating, and cooling pigment, are synoptically presented to show the broad application prospect of HEOs. Lastly, the intelligence-guided design and high-throughput screening of HEOs are briefly introduced to point out future development trends, which will become powerful tools to realize the customized design and synthesis of HEOs with optimal composition, structure, and performance for specific applications.

Plasma‐assisted fabrication of multiscale materials for electrochemical energy conversion and storage

AbstractPlasma, the fourth state of matter, is characterized by the presence of charged particles, including ions and electrons. It has been shown to induce unique physical and chemical reactions. Recently, there have been increased applications of plasma technology in the field of multiscale functional materials' preparation, with a number of interesting results. This review will begin by introducing the basic knowledge of plasma, including the definition, typical parameters, and classification of plasma setups. Following this, we will provide a comprehensive review and summary of the applications (phase conversion, doping, deposition, etching, exfoliation, and surface treatment) of plasma in common energy conversion and storage systems, such as electrocatalytic conversion of small molecules, batteries, fuel cells, and supercapacitors. This article summarizes the structure–performance relationships of electrochemical energy conversion and storage materials (ECSMs) that have been prepared or modified by plasma. It also provides an overview of the challenges and perspectives of plasma technology, which could lead to a new approach for designing and modifying electrode materials in ECSMs.

Insight into Magnesium Doping on Morphology, Optical, and Electrical Properties of Cu2O Layer Synthesized by Electrodeposition Method

Cu2O stands out as a promising semiconductor material for solar energy conversion, primarily due to its exceptional light-absorbing qualities and its widespread availability. However, its efficiency is somewhat hindered by its relatively low carrier mobility and a limited absorption band for carriers. The introduction of magnesium (Mg) doping into Cu2O has emerged as a potential means to enhance its morphology, optical characteristics, and electrical properties, making it an intriguing avenue for exploration. To fabricate the Mg-doped Cu2O layers, an electrodeposition process was employed on an Indium Tin Oxide (ITO) substrate. The resulting films were then subjected to characterization using Field Emission Scanning Electron Microscopy (FESEM), Ultraviolet-Visible Spectroscopy (UV-Vis), and HALL Effect Measurement, focusing on their morphology, optical properties, and electrical behaviors. Notably, the concentration of magnesium played a significant role in shaping the properties of the Cu2O layer. The fabrication process extended up to a dopant concentration of 0.3 M for both undoped Cu2O and Mg-doped Cu2O layers, leading to morphological alterations. Specifically, the grain size increased with varying dopant concentrations, but it became smaller and more compact after doping with 0.3 M Mg. The average absorbance of visible light for both undoped and Mg-doped Cu2O layers fell within the range of 1~2 au. Intriguingly, a doping level of 0.3 M Mg led to the simultaneous achievement of high carrier mobility (29.98 cm2/Vs), low bulk carrier concentration (2.3.928 x 1021 cm-3), and high resistivity (5.3 x 10-5 Ω cm) in the Cu2O material. Additionally, Cu2O/ITO thin films exhibiting rectifying characteristics were successfully fabricated, confirming the semiconductor nature of the deposited p-type Cu2O layer. The primary objective of this study was to synthesize Cu2O layers doped with varying concentrations of Mg and thoroughly characterize their morphology, optical attributes, and electrical behaviors through the electrodeposition method. The study findings and implications were extensively discussed.

Interaction and kinetics of H2, CO2, and H2O on Ti3C2Tx MXene probed by X-ray photoelectron spectroscopy

One of the most explored MXenes is Ti3C2Tx, where Tx is designated to inherently form termination species. Among many applications, Ti3C2Tx is a promising material for energy storage, energy conversion, and CO2-capturing devices. However, active sites for adsorption and surface reactions on the Ti3C2Tx-surface are still open questions to explore, which have implications for preparation methods when to obtain correct and optimized surface requirements. Here we use X-ray photoelectron spectroscopy (XPS) to study the adsorption of common gas molecules such as H2, CO2, and H2O, which all may be present in energy storage, energy converting, and CO2-capturing devices based on Ti3C2Tx. The study shows that H2O, with a strong bonding to the Ti-Ti bridge-sites, can be considered as a termination species. An O and H2O terminated Ti3C2Tx-surface restricts the CO2 adsorption to the Ti on-top sites and may reduce the ability to store positive ions, such as Li+ and Na+. On the other hand, an O and H2O terminated Ti3C2Tx-surface shows the capability to split water. The results from this study have implications for the correct selection of MXene preparations and the environment around the MXene in different implementations, such as energy storage, CO2-capturing, energy conversion, gas sensing, and catalysts.

Modulating the Doping Effect for Carbon Nanotube-Based Thermoelectric Composites by Radical-Containing Naphthalene Diimides.

Carbon nanotube-based organic thermoelectric composites have garnered a significant amount of research interest due to their synergistic benefits of the high electrical conductivity of carbon nanotubes and the low thermal conductivity of organic materials. Nevertheless, the correlation between the organic molecular structures and the thermoelectric properties of these composite systems has remained largely unexplored. This study delves into the doping effects of radical-containing naphthalene diimides (NDIs) on single-walled carbon nanotubes (SWCNTs) through molecular engineering. It finds that the structures of radical groups crucially impact the frontier energy levels of NDI molecules, thus influencing doping effects on SWCNTs. Conjugated phenoxy radicals enhance p doping, yielding superior n-type thermoelectric properties, while nonconjugated radicals promote n doping, enhancing p-type characteristics. This work highlights the enormous potential of molecular engineering through modulating doping effects for novel TE materials in energy conversion and utilization applications.

Facile and ecofriendly green synthesis of Co3O4/MgO-SiO2 composites towards efficient asymmetric supercapacitor and oxygen evolution reaction applications.

The development of low-cost, eco-friendly, and earth-friendly electrode materials for energy storage and conversion applications is a highly desirable but challenging task for strengthening the existing renewable energy systems. As part of this study, orange peel extract was utilized to synthesize a magnesium oxide-silicon dioxide hybrid substrate system (MgO-SiO2) for coating cobalt oxide nanostructures (Co3O4) via hydrothermal methods. A variety of MgO-SiO2 compositions were used to produce Co3O4 nanostructures. The purpose of using MgO-SiO2 substrates was to increase the porosity of the final hybrid material and enhance its compatibility with the electrode material. This study investigated the morphology, chemical composition, optical properties, and functional group properties. In hybrid materials, the shape structure is inherited from nanoparticles with uniform size distributions that are well compacted. A relative decrease in the optical band was observed for Co3O4 when deposited onto an MgO-SiO2 substrate. An improvement in the electrochemical properties of Co3O4/MgO-SiO2 composites was observed during the measurements of supercapacitors and oxygen evolution reaction (OER) in alkaline solutions. The Co3O4/MgO-SiO2 composite prepared on 0.4 g of the MgO-SiO2 substrate (sample 2) demonstrated excellent specific capacitance, high energy density, and recycling stability for 40 000 galvanic charge-discharge cycles. The assembled asymmetric supercapacitor (ASC) device demonstrated a specific capacitance of 243.94 F g-1 at a current density of 2 A g-1. Co3O4/MgO-SiO2 composites were found to be highly active towards the OER in 1 M KOH aqueous solution with an overpotential of 340 mV at 10 mA cm-2 and a Tafel slope of 88 mV dc-1. It was found that the stability and durability were highly satisfactory. Based on the use of orange peel extract, a roadmap was developed for the synthesis of porous hybrid substrates for the development of efficient electrode materials for energy storage and conversion.

Molecular Engineering for Future Thermoelectric Materials: The Role of Electrode and Metal Components in Molecular Junctions.

As global temperatures increase due to climate change, the accumulation of excess heat on Earth presents a valuable resource that can be harnessed for electricity generation using thermoelectric materials. However, the intricate structures of bulk thermoelectric materials pose significant challenges to their comprehensive understanding and limit performance. Additionally, their relatively high production costs present practical obstacles. A promising solution to these issues lies in molecular control and the use of molecular junctions. Molecules are predicted to surpass the performance of existing bulk materials in energy conversion because they can be chemically tuned to achieve high thermoelectric efficiencies. This review identifies the thermoelectric parameters that affect the performance of molecular junctions. It also explores various experimental platforms for measuring thermoelectric performance from single molecules to assemblies of hundreds of molecules. Finally, it highlights recent advancements in thermoelectric molecular junctions, focusing on the crucial roles of electrodes and metal components within the molecules, such as Ru complexes, metalloporphyrins, metallocenes, conjugated silane wires, and endohedral metallofullerenes. Ultimately, our review provides a comprehensive analysis of strategies to enhance the thermoelectric efficiency of molecular junctions.

(Europe Section Alessandro Volta Medal) Structure, Reactivity and Durability of Hybrid Functional Materials in Electrocatalysis: CO2-Reduction Versus N2-Fixation

Our research interests aim at establishing structure/property relations leading to rational designs of functionalized materials for efficient electrocatalysis and electrochemical energy conversion and storage. There has been growing interest in the electrochemical reduction of carbon dioxide, a potent greenhouse gas and a contributor to global climate change. Given the fact that the CO2 molecule is very stable, its electroreduction processes are characterized by large overpotentials. To optimize the hydrogenation-type electrocatalytic approach, we have proposed to utilize nanostructured metallic centers (e.g. Pd, Pt or Ru) in a form of highly dispersed and reactive nanoparticles generated within supramolecular network of distinct nitrogen, sulfur or oxygen-coordination complexes. Among important issues are the mutual completion between hydrogen evolution and carbon dioxide reduction and specific interactions between coordinating centers and metallic sites. We have also explored the ability of biofilms to form hydro-gel-type aggregates of microorganisms attached to various surfaces including those of carbon electrode materials. Upon incorporation of various noble metal nanostructures and/or conducting polymer ultra-thin films, highly reactive and selective systems toward CO2-reduction have been obtained. Another possibility to enhance electroreduction of carbon dioxide is to explore direct transformation of solar energy to chemical energy using transition metal oxide semiconductor materials. We show here that, by intentional and controlled combination of metal oxide semiconductors (titanium (IV) oxide and copper (I) oxide), we have been able to drive effectively photoelectrochemical reduction of carbon dioxide mostly to methanol.Application of metal oxides as active matrices in electrocatalysis is particular importance. The hydrous behavior, which favors proton mobility and affects overall reactivity, reflects not only the oxide’s chemical properties but its texture and morphology as well. For example, the mixed WO3/ZrO2 systems are characterized by fast charge (electron, proton) propagation during the system’s redox transitions. By dispersing metallic Cu electrocatalytic nanoparticles over such active WO3/ZrO2 supports, the electrocatalytic activities of the respective systems toward the reduction of carbon dioxide have been enhanced even at decreased loadings in acid media. The fact that WO3/ZrO2 nanostructures are in immediate contact with the metallic catalytic sites leads to the specific interactions (via the surface hydroxyl groups) with the reaction intermediates (e.g. CO adsorbates).Formation of ammonia is one of the most important chemical synthetic processes. Under industrial conditions, ammonia is primarily been synthesized from nitrogen and hydrogen via the Haber-Bosch process which requires pressurizing and heating, despite utilization of catalysts. Consequently, development of low-temperature synthetic methodology is tempting both from the practical and fundamental reasons. An ultimate goal for electrochemistry is to generate NH3 from N2 at temperatures lower than 100ºC, atmospheric pressure, and with use of new generation of catalysts. Currently, most of electrochemical approaches to drive N2-fixation suffer from slow kinetics due to the difficulty of achieving the appropriate adsorption and activation of dinitrogen molecule leading to cleavage of the strong triple N≡N bond. Our recent studies, clearly demonstrate that coordinatively stabilized iron catalytic sites, e.g. iron-centered heme-type porphyrins or iron phosphide, FeP and Fe2P phases, have been found to act as efficient catalysts for the formation of NH3 in alkaline and semi-neutral media.

Porous Silicon-Supported Catalytic Materials for Energy Conversion and Storage.

Porous silicon (Si) has a tetrahedral structure similar to that of sp3-hybridized carbon atoms in a typical diamond structure, which affords it unique chemical and physical properties including an adjustable intrinsic bandgap, a high-speed carrier transfer efficiency. It has shown great potential in photocatalysis, rechargeable batteries, solar cells, detectors, and electrocatalysis. This review introduces various porous Si-supported electrocatalysts and analyzes the reasons why porous Si is used as a new carrier/active sites from the perspectives of its molecular structure, electronic properties, synthesis methods, etc. The electrochemical applications of porous Si-based electrocatalysts in energy conversion reactions such as hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, and total water decomposition together with lithium-ion battery and supercapacitor in energy storage are summarized. The challenges and future research directions for porous Si are also discussed. This review aims to deepen the understanding of porous Si and promote the development and applications of this new type of Si material.

Ligand-assisted synthesis of novel π-SnS tetrahedrons for enhanced photocatalytic H2 evolution from water

Tin sulfide (SnS) is a potentially promising chalcogenide material for efficient solar energy conversion. In this study, pure π-SnS particles with a novel cubic phase were successfully synthesized by a simple one-pot solvothermal reaction method. The effects of solvothermal reaction time and amount of the ligand, hexamethyldisilazane (HMDS), on physical and photocatalytic properties were investigated. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray diffraction revealed that the obtained π-SnS consisted of tetrahedral particles with a high degree of crystallinity and exhibited a cubic phase. UV-Vis transmission spectra and photoluminescence (PL) revealed that the bandgap of π-SnS particles was about 1.62 eV. Importantly, the H2 evolution capacity of π-SnS particles prepared with Tin-HMDS complexes was dramatically improved. About 12-fold and 23-fold larger amounts of H2 were produced than the amounts produced by π-SnS particles prepared without HMDS and α-SnS particles with similar size, respectively. Post-annealing treatment further confirmed the existence of surface ligands and their importance for the photocatalytic activity of particles. X-ray photoelectron spectroscopy (XPS) revealed HMDS ligands instead of oleylamine molecules interacted with π-SnS particles.