In the quest to develop next-generation lithium batteries to meet the expansive consumer energy demands, batteries based on conversion chemistry are explored. Selenium cathodes have recently gained attention due to their high conductivity and volumetric capacity compared to the existing sulfur-based cathodes. The practical implementation of lithium–selenium batteries is often hindered by the rapid capacity fading due to the poor electronic contact and the shuttle effect caused by polyselenides. By encapsulating selenium in conducting cavities and using a suitable catalyst, we can mitigate the effect of polyselenide shuttling. Herein, we demonstrate a facile strategy to synthesise carbon sphere reactors loaded with catalytically active silver nanoparticles at the centre that act as efficient selenium hosts for Li–Se batteries. Selenium-encapsulated carbon spheres are prepared by a simple microwave synthesis method followed by carbonization and selenisation. The role of these catalytic nanoreactor centres in improving the capacity, cycling stability, and rate capability of Li–Se batteries is thoroughly investigated. The improved discharge capacity and the excellent cycling stability (249 mA h g−1 at 1C rate for 1000 cycles) are accounted for by the successful immobilization of selenides and polyselenides within the porous structure of the carbon spheres triggered by the silver catalyst.

Non-alkaline Zn–air batteries (ZABs) attract great attention because they can potentially combine high energy density, safety, and low cost. However, cathodes for non-alkaline ZABs are underdeveloped and suffer from poor charge–discharge kinetics. Here we study N-doped hierarchically porous carbons, which are synthesized using a self-templating approach, as catalytic scaffolds for oxygen reduction and oxygen evolution reactions (ORR and OER) in near-neutral media. Interestingly, although nitrogen doping does not improve the OER performance or carbon corrosion rate during the OER, it leads to a significant boost of the ORR kinetics in non-alkaline ZABs. Specifically, the reported N-doped hierarchically porous carbons outperform their nitrogen-free hierarchically porous analog, as well as the best commercially available nitrogen-free carbons. These results show that N-doped carbons can serve as promising support materials for non-alkaline ZABs.

High oxide-ion and proton conductivity in perovskite oxides has been well documented in the literature. Herein, we report a highly oxygen deficient perovskite oxide BaTa0.5Li0.5O2.5 (BTLO) as a new oxide-ion conductor. The material exhibits a simple primitive cubic perovskite structure (S.G.: Pmm) with lattice parameter a = 4.1024(1) Å and completely disordered Ta and Li cations on the B-site. The ionic conduction is predominated by oxide-ion over a wide range of oxygen partial pressure and temperature, with an ionic conductivity comparable to the state-of-the-art yttria-stabilized zirconia. Ab initio molecular dynamics (AIMD) simulations reveal that oxide-ion diffusion follows three-dimensional pathways, involving oxygen vacancy hopping along the edges of (Ta/Li)O4 tetrahedra and (Ta/Li)O6 octahedra. This work may inspire future work to discover new oxide-ion conductors in similar systems.

The massive quantity of glycerol produced due to the rapid expansion of biodiesel production requires its transformation into value-added products utilizing novel and sustainable methods. Here we report the microwave-induced production of solketal from glycerol using banana (Musa acuminata) peel waste functionalized with sulfonic acid as a heterogeneous catalyst. FTIR, PXRD, TGA, SEM-EDX, and TEM techniques were used to examine the chemical composition and morphology of the catalyst. The four parameters, the glycerol to acetone molar ratio (GTAR), reaction time, catalyst wt.%, and reaction temperature, were optimized using central composite design (CCD). 94.89% glycerol conversion to solketal was observed with a catalyst loading of 7 wt.%, a GTAR of 1 : 4, a reaction temperature of 65 °C, and a reaction time of 12 min. The catalyst showed remarkable stability when used repeatedly and could be reused at least five times without substantial reduction in its activity. With an activation energy of 40.23 kJ mol−1, the reaction followed pseudo-first-order kinetics. The thermodynamic analysis established the endothermic and non-spontaneous nature of the acetalization reaction. Therefore, this technique of glycerol valorization could be applied to the production of solketal as a biofuel additive on an industrial scale with further optimization.

Proton exchange membrane water electrolysis (PEMWE) is a promising sustainable hydrogen production technology that can be effectively coupled with intermittent renewable energy. Currently, iridium (Ir) based catalysts are used that can well balance catalytic activity and stability in water oxidation. Herein, our attention is directed to the recent progress of Ir-based catalysts employed in PEMWE. We first briefly outline the basic working principle of PEMWE, key components, and their functions in the devices. Then, the latest progress of Ir-based anode catalysts and their practical applications in PEMWE are introduced in detail from the aspects of Ir-based single metals, Ir-based alloys, Ir-based oxides, and some supported Ir-based catalysts. Finally, the current problems and challenges faced by Ir-based anode catalysts in future development are commented on. It is concluded that the intrinsic catalytic activity can be significantly improved through precise structural design, morphology control, and support selection. Due to the strong corrosion under acidic conditions, the anti-dissolution of Ir active species should be carefully considered for catalyst fabrication in the future. Hopefully, the current efforts can help understand the current state of Ir-based anode catalysts and develop novel and effective catalysts for application in practical PEMWE.

The development of advanced energy storage technologies has assumed paramount significance in addressing the escalating demands for sustainable and eco-friendly power sources. Amongst these innovative technologies, potassium-ion batteries (KIBs) have risen to the fore as viable contenders, chiefly owing to their cost-effectiveness and the abundant availability of potassium resources. Nevertheless, the realisation of efficient and high-performance KIBs hinges significantly upon the adept design and appropriate utilisation of cathode materials. Thus, this Perspective provides a comprehensive analysis of the present status, associated challenges, and prospective avenues concerning cathode materials for KIBs. We commence by discussing the significance of KIBs in the context of the global energy landscape and highlight their potential to revolutionise energy storage systems. Subsequently, we delve into cathode materials for KIBs, emphasising their pivotal role in determining the overall performance of these batteries. A systematic survey of the various cathode materials explored to date is presented, primarily encompassing layered oxides, polyanion-based compounds, Prussian analogues and organic moieties. The discussion focuses on the advantages, limitations, and performance metrics of each material class, unveiling the critical insights gained from experimental studies and theoretical investigations. Furthermore, this Perspective sheds light on the prominent challenges and obstacles hindering the widespread adoption of KIBs. These challenges include issues related to limited specific capacities, sluggish kinetics, and performance attenuation during cycling, as well as the scarcity of suitable electrolytes. We offer an authoritative evaluation of the efforts undertaken to address these obstacles, including novel material design strategies, advanced characterisation techniques, and the integration of nanotechnology. Finally, we conclude with a forward-looking perspective, outlining the future directions and potential breakthroughs in electrode materials for KIBs. We emphasise the importance of interdisciplinary collaborations, advancements in computational methods, and fundamental research to foster the development of high-performance and environmentally sustainable KIBs. In conclusion, this Perspective consolidates the current state of electrode materials for KIBs whilst elucidating the challenges that need to be overcome to unlock their full potential. By synthesising the collective knowledge from the latest research endeavours, this Perspective aims to inspire future research and innovation in the pursuit of efficient and scalable KIB technologies.

This study reports the design and operation of a power-to-gas system producing 240 kW of synthetic natural gas (SNG) from biogas and PV electricity. The system is composed of a solar field, an electrolyser, a plate-type heat exchanger methanation reactor and the required ancillary units. Biogas is cleaned from undesired components (such as H2S) and the raw gas including methane and CO2 is directly processed in the reactor. The process consumes biogas and renewable electricity to produce SNG and high-pressure steam from the methanation waste heat. The process efficiency in this configuration is 76%. The methanation reactor produces grid compliant SNG in all the load cases tested and in all the biogas composition cases. The reactor shows an excellent flexibility at the start-up, as grid-compliant SNG is produced in less than 10 minutes from feed start in hot-standby. Additionally, the reactor adapts in few minutes to load changes. The reactor is modelled to better understand the origin of the excellent performance in the biogas methanation reaction. It was found that the plate-type heat exchanger operated with boiling water as cooling is an ideal solution for the methanation reaction as it approximates well the optimal reaction pathway in terms of temperature and conversion profile. Large cooling is available where needed, preventing the operation at too high temperature. Isothermal conditions are established at the end of the reactor, allowing reaching the required high conversion.

Anodic dissolution of aluminum (commonly called aluminum corrosion) is a potential issue in sodium-ion batteries. Herein, it is demonstrated how different sodium-ion battery electrolyte solutions affect this phenomenon. The type of electrolyte was critical for the presence of anodic dissolution, while the solvent appeared to alter the dissolution process.

In this study, a facile synthesis route for preparing manganese dioxide (MnO2) with unique nano-needle morphology and its nanocomposite with reduced graphene oxide (MnO2–rGO) for high energy density quasi-solid-state asymmetric supercapacitor (ASC) application is reported. Morphological characterizations indicate that the MnO2 nano-needles are uniformly decorated on rGO sheets, creating an interconnected structure with rGO. The MnO2–rGO nanocomposite shows good pseudocapacitive electrochemical behavior in a potential domain from 0 to 1.0 V. The detailed analysis of the cyclic voltammetry (CV) profiles of the rGO and MnO2–rGO electrodes indicate that their sodium ion storage kinetics are based on ideal capacitive-controlled and pseudocapacitive (capacitive and diffusive) controlled processes, respectively. Furthermore, a quasi-solid-state ASC device is constructed by employing the MnO2–rGO nanocomposite and rGO as the positive and negative electrodes, respectively. The fabricated ASC (rGO‖MnO2–rGO) device operates within the wide cell potential range from 0 to 1.8 V and possesses the highest capacitance of 216 F g−1, at the current density of 1 A g−1, which is superior to that of the recently reported literatures. The ASC (rGO‖MnO2–rGO) device displays an energy density of 24.25 W h kg−1 at corresponding power density of 900 W kg−1 along with significant cycle stability over the 6000 cycles. Thus, the morphological design of an advanced electrode material to boost the capacitance and potential window with the polymer gel electrolyte will aid in the fabrication of high energy density storage devices.

The vast availability and environmental benignity of polysulfide–ferricyanide redox flow batteries (PSFRFBs) have attracted much deserving attention. However, the commercial scalability of polysulfide-based batteries is hindered by the expensive commercial ion exchange membrane and also the sluggish kinetics of polysulfide. Herein, we report an economically viable, thermally annealed PVDF-co-HFP-based cation exchange membrane (T-CEM). Thermal densification of the membrane mitigated the cross-contamination of polysulfide and ferro/ferri species across the membrane, whereas controlled sulfonation allowed smooth conduction of charge carriers. The diffusion coefficient values were 4.57 × 10−11 and 3.05 × 10−12 dm2 s−1 for polysulfide and ferricyanide, respectively, better than those of commercial separators. The polarization curve experiment depicted a power density of 220 mW cm−2 at 400 mA cm−2 current density. The flow battery exhibited capacity retention of 88% with average capacity decay of 0.12% per cycle, 99.4% coulombic efficiency and 63.0% energy efficiency over 250 uninterrupted charge/discharge cycles at 40 mA cm−2 current density, and the long durability characteristic revealed high efficacy and the best usability in PSFRFBs. Furthermore, the facile densification strategy demonstrated in this work can be employed to fabricate better ion exchange membranes for energy device applications and separation/purification.

Tuning the band structure by doping metal elements is an effective way to boost charge transfer and thus improve the photocatalytic activity of polymeric carbon nitride (CN). Herein, Mo-doped carbon nitride (Mo–CN) was prepared by calcining melamine, cyanuric acid and sodium molybdate at elevated temperature. Under visible light at λ ≥ 420 nm, the optimal hydrogen production rate of 3Mo–CN reaches 16.7 μmol h−1, about eight times that of pristine CN. Experimental results demonstrate that Mo doping reduces the band gap, increases the specific surface area, extends the visible light harvesting range, and enhances the separation and transfer of photogenerated carriers. Theoretical simulation verifies that the intercalated Mo acts as a bridging channel for interlayer charge transfer, increases the intramolecular electron transition distance (Dct) and charge transfer quantity, and enhances the localization of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). All these factors are interwoven to contribute to the enhanced photocatalytic performance of polymeric carbon nitride.

We report on the mechanical properties of high-efficiency perovskite solar cells (PSCs) with different chemical components by measuring the fracture energy (Gc) of films and devices. With the help of both macroscopic and microscopic techniques, we identify the locations where fracture takes place in the devices (either adhesive or cohesive failure) with various material and device structures. We propose strategies that can improve the fracture energy of PSCs based on the measured Gc: the use of ozone-nucleated atomic layer deposition to improve charge transport layer robustness and the use of 2D perovskites and morphology control to improve the perovskite robustness. Our findings offer a pathway to rationally study the mechanical properties of PSCs and enable such cells to be more mechanically robust to reach commercial viability.

Efficient coupling of economically favorable electro-oxidation reactions with the hydrogen evolution reaction (HER) has been considered as a promising way to realize synergistic production of hydrogen and value-added chemicals. In this work, a supported nickel molybdenum oxide catalyst was fabricated, which exhibits enhanced activity towards the benzyl alcohol oxidation reaction (BOR) benefited from the enriched active sites. Further investigations indicate that the nearly complete conversion from benzyl alcohol (BA) to the benzoic acid (BC) product can be achieved with simultaneously realized high selectivity and high faradaic efficiency (FE) for long-term operation. The efficient catalyst explored in this work could offer a new material platform for coupled production and value-added benzoic acid and hydrogen.

Harnessing and storage of solar radiations employing molecular photoswitches are certainly of intense research interest en route to alleviate the increasing energy demand. The present report aims to scrutinize the effect of N-Substitution on the photoswitching behaviour of bicyclodienes with different bridge lengths for molecular solar thermal energy storage (MOST) application. The result reveals that the bicyclodiene attains stability with an increase in bridge length due to a decreasing ring strain, while the photoproduct acquires strain and becomes destabilized. Consequently, as the bridge length increases, the storage energy is enhanced while the back reaction barrier decreases. The photoswitching properties can be greatly altered based on the position of N in aza-bicyclodiene. Aza-bicyclodiene photoswitches are isobaric with the parent systems and do not reduce the energy storage density, unlike the bulky electron releasing and withdrawing substituents. N-substitution at the bridgehead position enhances the thermal back reaction barrier without compromising the storage energy in long-bridged switches. Further, N-substitution is effective at shifting (bathochromic) the excitation wavelength to the longer wavelength region of the spectrum. Therefore, N-substitution in long-bridge bicyclodiene photoswitches could be beneficial to improve the thermochemical as well as photophysical properties for MOST application.

Lithium metal batteries possess remarkable energy storage capabilities, but their commercial realization is hindered by challenges in controlling the reactivity of lithium. Interfacial engineering has emerged as a promising strategy for addressing lithium reactivity. In this article, we discuss several key interfacial engineering approaches used to stabilize lithium metal at lithium–electrolyte and lithium–current collector interfaces. We examine these commonly employed interfacial engineering methods and highlight unresolved questions crucial for advancing the understanding of lithium reactivity. Our discussion highlights the potential of interfacial engineering tools to enhance our understanding of and overcome the challenges associated with lithium reactivity.

A novel process is applied in a pilot plant integrated within a steel mill in Saarland, Germany, in which the greenhouse gases CO2 and CH4 are converted into synthesis gas, a mixture of H2 and CO, by homogeneous dry reforming. The process is based on heating a gas mixture of coke oven gas (COG) and blast furnace gas (BFG) to high temperatures in a regenerative heat exchanger, similar to the existing hot blast stoves used to heat the hot blast blown into the blast furnace. The resulting synthesis gas can be injected into the blast furnace at the level of the shaft and/or tuyere, reducing coke consumption in iron production, potentially leading to a reduction in global CO2 emissions of about 0.5%. After commissioning, the cyclic operating pilot plant was used to study a wide variation of operating parameters. At a maximum local peak temperature of over 1721 K during the synthesis gas production phase, an average conversion of about 97% for CH4 and over 94% for CO2 was achieved, which is close to the thermodynamic equilibrium of over 99% and about 98%, respectively. The scale-up process is accomplished by modeling and numerical simulation. The measured data obtained from the pilot plant agree well with the numerical simulations using a detailed elementary-step reaction mechanism.

In the context of developing novel fuel cell catalysts, we have successfully synthesized in high yields not only ultrathin nanowires with compositions of Pt1Ru1 and Pt3Ru1 but also more complex spoke-like dendritic clusters of Pt1Ru1 and Pt1Ru9 in ambient pressure under relatively straightforward, solution-based reaction conditions, mediated by either cetyltrimethylammonium bromide (CTAB) or oleylamine (OAm), respectively. EXAFS analysis allowed us to determine the homogeneity of the as-prepared samples. Based on this analysis, only the Pt3Ru1 sample was found to be relatively homogeneous. All of the other samples yielded results, suggestive of a tendency for the elements to segregate into clusters of ‘like’ atoms. We have also collected complementary HRTEM EDS mapping data, which support the idea of a segregation of elements consistent with the EXAFS results. We attribute the differences in the observed morphologies and elemental distributions within as-prepared samples to the presence of varying surfactants and heating environments, employed in these reactions. Methanol oxidation reaction (MOR) measurements indicated a correlation of specific activity (SA) values not only with intrinsic chemical composition and degree of alloying but also with the reaction process used to generate the nanoscale motifs in the first place. Specifically, the observed performance of samples tested decreased as a function of chemical composition (surfactant used in their synthesis), as follows: Pt3Ru1 (CTAB) > Pt1Ru1 (CTAB) > Pt1Ru1 (OAm) > Pt1Ru9 (OAm).

With the gradual development of renewable energy technologies, developing metal-free carbon materials has attracted more attention as a new category of multifunctional electrocatalysts. Along with the deepening of the comprehension of the electrocatalytic nature, the electrocatalytic performance of carbon catalysts could be greatly regulated by embellishing with foreign atoms and pores. Herein, we synthesized a three dimensional N, P, O co-doped carbon framework (3D-NPOC) by using a simple annealing treatment with tannic acid as a precursor. Benefitting from the electronic structure optimization effect of foreign atoms and accelerated electrolyte transfer and gas diffusion derived from the interconnected 3D porous nanostructures, the obtained 3D-NPOC showed a relatively high ORR half-wave potential that is on a par with those of commercial Pt/C, delivered a comparable OER performance to IrO2, especially under high current densities, and also showcased comparatively good HER properties. More importantly, the obtained catalyst-based zinc–air batteries exhibited a comparable performance to Pt/C‖IrO2-based batteries.

Although lithium excess cation-disordered rock salt (DRX) metal oxides have been identified as promising candidates for positive-electrode materials, their actual potential remains unclear because previous studies have used inappropriate technological parameters, such as low mass loadings or excessive amounts of electrolyte. In this study, Li2RuO3/Li2SO4 was selected as the model DRX material, and its performance was investigated under cell-level high-energy-density conditions. A highly-mass-loaded positive electrode (30 mg cm−2) with an active material ratio exceeding 96% was fabricated by suppression of the gelation of slurry solution during the electrode preparation process, which is achieved by proper control of the particle size of Li2RuO3/Li2SO4. Notably, using a protected lithium metal electrode setup, superior capacity of the Li2RuO3/Li2SO4 electrode over 180 mA h g−1 was achieved over the 80th cycle under high mass loading and lean electrolyte conditions. The results obtained in the present study reveal the potential of the DRX based positive electrode for realizing superior performance even under practical cell conditions.

As Li-metal anodes become more readily available, next-gen Li-ion battery cathodes are no longer required to contain Li in their as-synthesized state, vastly expanding the materials search space. In order to identify potential cathode materials that do not necessarily contain Li in their native state, we here develop a computational screening pipeline for rapid cathode discovery. This pipeline operates on any database of inorganic materials without a priori information on Li sites and performs screening based on computed voltage, capacity from sequential insertions of Li ions and most importantly, mobility built upon the graph-based migration network obtained through site connectivity. A preliminary application of the pipeline was carried out on a subset of the materials project database, and one particular polymorph of MnP2O7 is shown here as an example of a new candidate compound which completed the pipeline and was selected for further, detailed analysis. The compound is shown to present a 2D ion migration topology, consisting of two separate intercalation pathways where the corresponding energy landscapes are calculated with the nudged-elastic band formalism. Acceptable energy barriers are found in the dilute (highly charged) limit, however the material is expected to exhibit slower kinetics in the vacancy (highly discharged) limit.