Solar-driven energy conversion is a promising technology for a sustainable energy future and environmental remediation, and an efficient catalyst is a key factor. Recently, metal halide perovskites (MHPs) have emerged as promising photocatalysts due to their exceptional photoelectronic properties and low-cost solution processing, enabling successful applications in H2 evolution, CO2 reduction, organic synthesis, and pollutant degradation. Despite these successes, the practical applications of MHPs are limited by their water instability. In this review, the recently developed strategies driving MHP-catalyzed reactions in aqueous media are outlined. We first articulate the structures and properties of MHPs, followed by elaborating on the origin of instability in MHPs. Then, we highlight the advances in solar-driven MHP-based catalytic systems in aqueous solutions, focusing on developing external protection strategies and intrinsically water-stable MHP materials. With each approach offering peculiar sets of advantages and challenges, we conclude by outlining potentially promising opportunities and directions for MHP-based photocatalysis research in aqueous conditions moving forward. We anticipate that this timely review will provide some inspiration for the design of MHP-based photocatalysts, manifestly stimulating their applications in aqueous environments for solar-to-chemical energy conversion.
The use of solar energy to produce hydrogen has been one of the research hotspots in recent years. With the continuous exploitation of solar hydrogen evolution, the performance of photo(electro)catalysts has been greatly optimized. However, the solar-driven hydrogen production for most semiconductors, especially for organic semiconductors, is limited due to the lack of active centers and serious electron–hole recombination. Recently, it has been reported that carbon-carbon triple bonds (C≡C) can function as active sites for hydrogen evolution, and diacetylenic moiety in organic semiconductors is able to increase carrier migration as well. Therefore, organic semiconductors containing C≡C have attracted considerable attention in the past few years. In this review, organic materials or organic–inorganic hybrids containing C≡C for photo(electro)catalytic solar hydrogen production are classified first, including graphdiyne, conjugated acetylene polymers, some covalent organic frameworks, and metal–organic frameworks. After that, the structure, properties, and advantages and disadvantages of C≡C-containing materials are introduced and summarized. Apart from these, this review also presents advances in materials containing C≡C in the field of solar hydrogen generation. Finally, perspectives on the future development of C≡C-containing materials in the field of solar hydrogen generation are also briefly anticipated. This review provides pertinent insights into the main challenges and potential advances in the organic semiconductors for solar-driven hydrogen production, which will also greatly contribute to other photo(electro)catalytic reactions.
The path to searching for sustainable energy has never stopped since the depletion of fossil fuels can lead to serious environmental pollution and energy shortages. Using water electrolysis to produce hydrogen has been proven to be a prioritized approach for green resource production. It is highly crucial to explore inexpensive and high-performance electrocatalysts for accelerating hydrogen evolution reaction (HER) and apply them to industrial cases on a large scale. Here, we summarize the different mechanisms of HER in different pH settings and review recent advances in non-noble-metal-based electrocatalysts. Then, based on the previous efforts, we discuss several universal strategies for designing pH-independent catalysts and show directions for the future design of pH-universal catalysts.
Metal halide perovskite (MHP) quantum dots (QDs) offer immense potential for several areas of photonics research due to their easy and low-cost fabrication and excellent optoelectronic properties. However, practical applications of MHP QDs are limited by their poor stability and, in particular, their tendency to aggregate. Here, we develop a two-step double-solvent strategy to grow and confine CsPbBr3 QDs within the three-dimensional (3D) cavities of a mesoporous SBA-16 silica scaffold (CsPbBr3@SBA-16). Strong confinement and separation of the MHP QDs lead to a relatively uniform size distribution, narrow luminescence, and good ambient stability over 2 months. In addition, the CsPbBr3@SBA-16 presents a high activity and stability for visible-light-driven photocatalytic toluene C(sp3)–H bond activation to produce benzaldehyde with ˜730 µmol g–1 h–1 yield rate and near-unity selectivity. Similarly, the structural stability of CsPbBr3@SBA-16 QDs is superior to that of both pure CsPbBr3 QDs and those confined in MCM-41 with 1D channels.
In the quest for sustainable energy materials, wood is discovered to be a potential piezoelectric material. However, the rigidity, poor stability, and low piezoelectric properties of wood impede its development. Here, we obtained a superelastic roasted wood nanogenerator (RW-NG) by unraveling ray tissues through a sustainable roasting strategy. The increased compressibility of roasted wood intensifies the deformation of cellulose microfibrils, significantly enhancing the piezoelectric effect in wood. Roasted wood (15 × 15 × 15 mm3, longitudinal × radial × tangential) can generate a voltage and current outputs of 1.4 V and 14.5 nA, respectively, which are more than 70 times that of natural wood. The wood sample can recover 90% of its shape after 5000 compressions at 65% strain, exhibiting excellent elasticity and stability. Importantly, roasted wood does not add any toxic substances and can be safely applied on the human skin as a self-powered sensor for detecting body movements. Moreover, it can also be assembled into self-powered wooden floors for energy harvesting. These indicate that roasted wood has great potential for sustainable sensing and energy conversion.
Thermally chargeable supercapacitors (TCSCs) have offered exceptional energy-converting efficiency for absorbing human epidermal heat and generating and storing electrical energy, which then realize continuous power supply to electronic devices, such as sensors and wearable electronic products, in a wide range of practical significance. Here, we proposed a flexible TCSC by attaching binder-free Ti3C2Tx MXene@PPy electrodes on both ends of the H3PO4@P(AM-co-AA-co-AYP K+) hydrogel electrolyte, which exhibits a large thermal power of 35.2 mV K–1 at 50% relative humidity and maximum figure of merit of 2.1. The high performances of the fabricated devices can be attributed to the tunable electrical, thermodynamic, thermoelectric, and mechanical properties of the hydrogel electrolyte by adjusting the acid content and the proportion of zwitterionic compound AYP K+ in the hydrogel, and the high photothermal conversion efficiency and electrochemical performance of the electrodes. Moreover, the stable and outstanding thermofvoltage output (˜200 mV) under different time scenarios of the TCSC makes it possible to drive a strain sensor, accomplishing the objectives of a human activity monitor.
The effectiveness of dual-doping as a method of improving the conductivity of sulfide solid electrolytes (SEs) is not in doubt; however, the atomic-level mechanisms underpinning these enhancements remain elusive. In this study, we investigate the atomic mechanisms associated with the high ionic conductivity of the Li7P3S11 (LPS) SE and its response to Ag/Cl dual dopants. Synthesis and electrochemical characterizations show that the 0.2 M AgCl-doped LPS (Li6.8P3Ag0.1S10.9Cl0.1) exhibited an over 80% improvement in ionic conductivity compared with the undoped LPS. The atomic-level structures responsible for the enhanced conductivity were generated by a set of experiment and simulation techniques: synchrotron X-ray diffractometry, Rietveld refinement, density functional theory, and artificial neural network-based molecular dynamics simulations. This thorough characterization highlights the role of dual dopants in altering the structure and ionic conductivity. We found that the PS4 and P2S7 structural motifs of LPS undergo transformation into various PSx substructures. These changes in the substructures, in conjunction with the paddle-wheel effect, enable rapid Li migration. The dopant atoms serve to enhance the flexibility of PS4–P2S7 polyhedral frameworks, consequently enhancing the ionic conductivity. Our study elucidates a clear structure–conductivity relationship for the dual-doped LPS, providing a fundamental guideline for the development of sulfide SEs with superior conductivity.
As a promising flexible energy source for next-generation emerging electronic devices, the temperature adaptability and low-temperature performance retention of flexible zinc-air batteries (ZABs) remain a great challenge for their practical application. Herein, we report photothermal-promoted aqueous and flexible ZABs with enhanced performance under a wide temperature range via using Ni-doped Mn3O4/N-doped reduced graphene oxide (denoted as Ni-Mn3O4/N-rGO) nanohybrids as bifunctional electrocatalysts. Upon being exposed to near-infrared light, the Ni-Mn3O4/N-rGO exhibited a powerful photothermal effect, resulting in localized and immediate heating of the electrode. Such effects led to increased active sites, improved electrical conductivity, enhanced release of bubbles, and promoted surface reconstruction of the electrode catalyst as corroborated by simulation and operando Raman. Consequently, the catalytic performance was boosted, manifesting a superior activity indicator ΔE of 0.685 V with excellent durability. As expected, the corresponding photothermal-assisted rechargeable ZABs possessed an excellent maximum power density (e.g., 78.76 mW cm–2 at –10°C), superb cycling stability (e.g., over 430 cycles at –10°C), and excellent flexibility from 25°C to subzero temperature. Our work opens up new possibilities for the development of all-climate flexible electronic devices.
Waste tyres (WTs) are a major global issue that needs immediate attention to ensure a sustainable environment. They are often dumped in landfills or incinerated in open environments, which leads to environmental pollution. However, various thermochemical conversion methods have shown promising results as treatment routes to tackle the WT problem while creating new materials for industries. One such material is WT char, which has properties comparable to those of carbon materials used as an active electrode material in batteries. Therefore, a systematic review of the various thermochemical approaches used to convert WTs into carbon materials for electrode applications was conducted. The review shows that pretreatment processes, various process routes, and operating parameters affect derived carbon properties and its respective electrochemical performance. WT-derived carbon has the potential to yield a high specific capacity greater than the traditional graphite (372 mAh g–1) commonly used in lithium-ion batteries. Finally, the review outlines the challenges of the process routes, as well as opportunities and future research directions for electrode carbon materials from WTs.
Rechargeable aqueous zinc batteries are promising for large-scale energy storage due to their low cost and high safety; however, their energy density has reached the ceiling based on conventional cathodes with a single cationic redox reaction mechanism. Herein, a highly reversible cathode of typical layered vanadium oxide is reported, which operates on both the cationic redox couple of V5+/V3+ accompanied by the Zn2+ storage and the anionic O–/O2– redox couple by anion hosting in an aqueous deep eutectic solvent electrolyte. The reversible oxygen redox delivers an additional capacity of ˜100 mAh g–1 at an operating voltage of ˜1.80 V, which increases the energy density of the cathode by ˜36%, endowing the cathode system a record high energy density of ˜506 Wh kg–1. The findings highlight new opportunities for the design of high-energy zinc batteries with both Zn2+ and anions as charge carriers.
Lithium-sulfur batteries (LSBs) have garnered attention from both academia and industry because they can achieve high energy densities (>400 Wh kg–1), which are difficult to achieve in commercially available lithium-ion batteries. As a preparation step for practically utilizing LSBs, there is a problem, wherein battery cycle life rapidly reduces as the loading level of the sulfur cathode increases and the electrode area expands. In this study, a separator coated with boehmite on both sides of polyethylene (hereinafter denoted as boehmite separator) is incorporated into a high-loading Li-S pouch battery to suppress sudden capacity drops and achieve a longer cycle life. We explore a phenomenon by which inequality is generated in regions where an electrochemical reaction occurs in the sulfur cathode during the discharging and charging of a high-capacity Li-S pouch battery. The boehmite separator inhibits the accumulation of sulfur-related species on the surface of the sulfur cathode to induce an even reaction across the entire cathode and suppresses the degradation of the Li metal anode, allowing the pouch battery with an areal capacity of 8 mAh cm–2 to operate stably for 300 cycles. These results demonstrate the importance of customizing separators for the practical use of LSBs.
Germanium (Ge)–air batteries have gained significant attention from researchers owing to their high power density and excellent safety. However, self-corrosion and surface passivation issues of Ge anode limit the development of high-performance Ge–air batteries. In this study, conductive metal-organic framework (MOF) Ni3(HITP)2 material was synthesized by the gas–liquid interface approach. The Ni3(HITP)2 material was deposited on the surface of the Ge anode to prevent corrosion and passivation reactions inside the battery. At 16°C, the discharge time of Ge anodes protected with MOFs was extended to 59 h at 195 µA cm–2, which was twice that of bare Ge anodes. The positive effect of MOFs on Ge–air batteries at high temperatures was observed for the first time. The Ge@Ni3(HITP)2 anodes discharged over 600 h at 65.0 µA cm–2. The experimental results confirmed that the two-dimensional conductive MOF material effectively suppressed the self-corrosion and passivation on Ge anodes. This work provides new ideas for improving the performance of batteries in extreme environments and a new strategy for anode protection in air batteries.
Atomically dispersed single-atom catalysts (SACs) on carbon supports show great promise for H2O2 electrosynthesis, but conventional wet chemistry methods using particulate carbon blacks in powder form have limited their potential as two-electron (2e–) oxygen reduction reaction (ORR) catalysts. Here, we demonstrate high-performance Co SACs supported on a free-standing aligned carbon nanofiber (CNF) using electrospinning and arc plasma deposition (APD). Based on the surface oxidation treatment of aligned CNF and precise control of the deposition amount in a dry-based APD process, we successfully form densely populated Co SACs on aligned CNF. Through experimental analyses and density functional theory calculations, we reveal that Co SAC has a Co–N2–O2 moiety with one epoxy group, leading to excellent 2e– ORR activity. Furthermore, the aligned CNF significantly improves mass transfer in flow cells compared to randomly oriented CNF, showing an overpotential reduction of 30 mV and a 1.3-fold improvement (84.5%) in Faradaic efficiency, and finally achieves an outstanding production rate of 15.75 mol gcat–1 h–1 at 300 mA cm–2. The high-performance Co SAC supported on well-aligned CNF is also applied in an electro-Fenton process, demonstrating rapid removal of methylene blue and bisphenol F due to its exceptional 2e– ORR activity.
Carbonate-electrolyte-based lithium–sulfur (Li–S) batteries with solid-phase conversion offer promising safety and scalability, but their reversible capacities are limited. In addition, large-format pouch cells are paving the way for large-scale production. This study demonstrates the in situ formation of a solid-electrolyte interphase (SEI) as a protective layer using vinylene carbonate (VC), highlighting its industrial adaptability. A high reversible capacity is achieved by the lithiated poly-VC SEI formed inside the cathode particles as a nanoscale ionic conduction path, along with the traditional surface protective layer. Furthermore, the severe dissolution of poly-VC is mitigated by LiF derived from fluorine ethylene carbonate as a co-solvent, enabling high rate performance and a long cycle life. A large 8 Ah pouch cell is successfully developed, which shows a high energy density of 400 Wh kg–1 based on the cell weight. This work demonstrates the high performance of large-scale Li–S batteries with the in situ formation of a protective layer as a scalable technique for future applications.
With the rapid advancement of terahertz technologies, electromagnetic interference (EMI) shielding materials are needed to ensure secure electromagnetic environments. Enormous efforts have been devoted to achieving highly efficient EMI shielding films by enhancing flexibility, lightweight, mechanical robustness, and high shielding efficiency. However, the consideration of the optical properties of these shielding materials is still in its infancy. By incorporating transparency, visual information from protected systems can be preserved for monitoring interior working conditions, and the optical imperceptibility allows nonoffensive and easy cover of shielding materials for both device and biology. There are many materials that can be applied to transparent EMI shields. In particular, two-dimensional transition metal carbide/nitrides (MXenes), possessing the advantages of superior conductivity, optical properties, favorable flexibility, and facile processibility, have become a great candidate. This work reviews the recent research on developing highly efficient and optically transparent EMI shields in a comprehensive way. Materials from MXenes, indium tin oxide, metal, carbon, and conductive polymers are covered, with a focus on the employment of MXene-based composites in transparent EMI shielding. The prospects and challenges for the future development of MXene-based transparent EMI shields are discussed. This work aims to promote the development of high-performance, optically transparent EMI shields for broader applications by leveraging MXenes.
Crystalline perovskite oxides are regarded as promising electrocatalysts for water electrolysis, particularly for anodic oxygen evolution reactions, owing to their low cost and high intrinsic activity. Perovskite oxides with noncrystalline or amorphous characteristics also exhibit promising electrocatalytic performance toward electrochemical water splitting. In this review, a fundamental understanding of the characteristics and advantages of crystalline, noncrystalline, and amorphous perovskite oxides is presented. Subsequently, recent progress in the development of advanced electrocatalysts for water electrolysis by engineering and breaking the crystallinity of perovskite oxides is reviewed, with a special focus on the underlying structure–activity relationships. Finally, the remaining challenges and unsolved issues are presented, and an outlook is briefly proposed for the future exploration of next-generation water-splitting electrocatalysts based on perovskite oxides.
Hydrogen peroxide (H2O2) is one of the 100 most important chemicals in the world with high energy density and environmental friendliness. Compared with anthraquinone oxidation, direct synthesis of H2O2 with hydrogen (H2) and oxygen (O2), and electrochemical methods, photocatalysis has the characteristics of low energy consumption, easy operation and less pollution, and broad application prospects in H2O2 generation. Various photocatalysts, such as titanium dioxide (TiO2), graphitic carbon nitride (g-C3N4), metal-organic materials, and nonmetallic materials, have been studied for H2O2 production. Among them, g-C3N4 materials, which are simple to synthesize and functionalize, have attracted wide attention. The electronic band structure of g-C3N4 shows a bandgap of 2.77 eV, a valence band maximum of 1.44 V, and a conduction band minimum of –1.33 V, which theoretically meets the requirements for hydrogen peroxide production. In comparison to semiconductor materials like TiO2 (3.2 eV), this material has a smaller bandgap, which results in a more efficient response to visible light. However, the photocatalytic activity of g-C3N4 and the yield of H2O2 were severely inhibited by the electron-hole pair with high recombination rate, low utilization rate of visible light, and poor selectivity of products. Although previous reviews also presented various strategies to improve photocatalytic H2O2 production, they did not systematically elaborate the inherent relationship between the control strategies and their energy band structure. From this point of view, this article focuses on energy band engineering and reviews the latest research progress of g-C3N4 photocatalytic H2O2 production. On this basis, a strategy to improve the H2O2 production by g-C3N4 photocatalysis is proposed through morphology control, crystallinity and defect, and doping, combined with other materials and other strategies. Finally, the challenges and prospects of industrialization of g-C3N4 photocatalytic H2O2 production are discussed and envisioned.
MAX phase ceramics is a large family of nanolaminate carbides and nitrides, which integrates the advantages of both metals and ceramics, in general, the distinct chemical inertness of ceramics and excellent physical properties like metals. Meanwhile, the rich chemical and structural diversity of the MAXs endows them with broad space for property regulation. Especially, a much higher self-lubricity, as well as wear resistance, than that of traditional alloys and ceramics, has been observed in MAXs at elevated temperatures in recent decades, which manifests a great application potential and sparks tremendous research interest. Aiming at establishing a correlation among structure, chemical composition, working conditions, and the tribological behaviors of MAXs, this work overviews the recent progress in their high-temperature (HT) tribological properties, accompanied by advances in synthesis and structure analysis. HT tribological-specific behaviors, including the stress responses and damage mechanism, oxidation mechanism, and wear mechanism, are discussed. Whereafter, the tribological behaviors along with factors related to the tribological working conditions are discussed. Accordingly, outlooks of MAX phase ceramics for future HT solid lubricants are given based on the optimization of present mechanical properties and processing technologies.
Lithium–sulfur (Li–S) battery is attracting increasing interest for its potential in low-cost high-density energy storage. However, it has been a persistent challenge to simultaneously realize high energy density and long cycle life. Herein, we report a synergistic strategy to exploit a unique nitrogen-doped three-dimensional graphene aerogel as both the lithium anode host to ensure homogeneous lithium plating/stripping and mitigate lithium dendrite formation and the sulfur cathode host to facilitate efficient sulfur redox chemistry and combat undesirable polysulfide shuttling effect, realizing Li–S battery simultaneously with ultrahigh energy density and long cycle life. The as-demonstrated polysulfide-based device delivers a high areal capacity of 7.5 mAh/cm2 (corresponds to 787 Wh/L) and an ultralow capacity fading of 0.025% per cycle over 1000 cycles at a high current density of 8.6 mA/cm2. Our findings suggest a novel strategy to scale up the superior electrochemical property of every microscopic unit to a macroscopic-level performance that enables simultaneously high areal energy density and long cycling stability that are critical for practical Li–S batteries.
Flexible electrode design with robust structure and good performance is one of the priorities for flexible batteries to power emerging wearable electronics, and organic cathode materials have become contenders for flexible self-supporting electrodes. However, issues such as easy electrolyte solubility and low intrinsic conductivity contribute to high polarization and rapid capacity decay. Herein, we have designed a flexible self-supporting cathode based on perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA), interfacial engineering enhanced by polypyrrole (PPy), and carbon nanotubes (CNTs), forming the interconnected and flexible PTCDA/PPy/CNTs using polymerization reaction and vacuum filtration methods, effectively curbing those challenges. When used as the cathode of sodium-ion batteries, PTCDA/PPy/CNTs exhibit excellent rate capability (105.7 mAh g–1 at 20 C), outstanding cycling stability (79.4% capacity retention at 5 C after 500 cycles), and remarkable wide temperature application capability (86.5 mAh g–1 at –30°C and 115.4 mAh g–1 at 60°C). The sodium storage mechanism was verified to be a reversible oxidation reaction between two Na+ ions and carbonyl groups by density functional theory calculations, in situ infrared Fourier transform infrared spectroscopy, and in situ Raman spectroscopy. Surprisingly, the pouch cells based on PTCDA/PPy/CNTs exhibit good mechanical flexibility in various mechanical states. This work inspires more rational designs of flexible and self-supporting organic cathodes, promoting the development of high-performance and wide-temperature adaptable wearable electronic devices.