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Supercapacitors (SCs) are gaining attention for Internet of Things (IoT) devices because of their impressive characteristics, including their high power and energy density, extended lifespan, significant cycling stability, and quick charge–discharge cycles. Hence, it is essential to make precise predictions about the capacitance and lifespan of supercapacitors to choose the appropriate materials and develop plans for replacement. Carbon-based supercapacitor electrodes are crucial for the advancement of contemporary technology, serving as a key component among numerous types of electrode materials. Moreover, accurately forecasting the lifespan of energy storage devices may greatly improve the efficient handling of system malfunctions. Researchers worldwide have increasingly shown interest in using machine learning (ML) approaches for predicting the performance of energy storage materials. The interest in machine learning is driven by its noteworthy benefits, such as improved accuracy in predictions, time efficiency, and cost-effectiveness. This paper reviews different charge storage processes, categorizes SCs, and investigates frequently employed carbon electrode components. The performance of supercapacitors, which is crucial for Internet of Things (IoT) applications, is affected by a number of their characteristics, including their power density, charge storage capacity, and cycle longevity. Additionally, we provide an in-depth review of several recently developed ML-driven models used for predicting energy substance properties and optimizing supercapacitor effectiveness. The purpose of these proposed ML algorithms is to validate their anticipated accuracies, aid in the selection of models, and highlight future research topics in the field of scientific computing. Overall, this research highlights the possibility of using ML techniques to make significant advancements in the field of energy-storing device development. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides exhibit various stacking polytypes and distinct electronic structures. In this study, first-principles calculations show that chalcogen enrichment induces the phase conversion from 2H to 1T′. Models for Se intercalation and substitution (MoSex and WSex with x > 2) were constructed for the 2H and three stacking polytypes of the 1T′ phase (1T′, 2M, and Td). Se intercalates and substitutes more favorably into the 1T′ polytypes than into the 2H phase. Intercalation in the 1T′ polytypes occurs by forming Se dimers, which is distinct from the Se monomer in the 2H phase. The relative stability predicts that as x increases, the 2H phase undergoes phase conversion preferentially into the 2M phase. On the experimental side, we synthesized Se-rich MoSe2 and WSe2 nanosheets using a colloidal reaction, and confirmed the stacking sequence of the 2M phase using atomic-resolution scanning transmission electron microscopy. The Se-rich 2M phase nanosheets exhibited enhanced electrocatalytic performance in the hydrogen evolution reaction (HER). Gibbs free energy calculations support that excess Se enhances the HER. [ABSTRACT FROM AUTHOR]

Semiconductor ionic electrolytes, especially heterostructure composites, have a significant role in enhancing oxide ion conductivity and peak power density (PPD) because of their interfacial contact. In this work, the fluorite structure CeO2 and spinel-based CoAl2O4 samples, as a heterostructure composite electrolyte, are successfully fabricated. The p-type CoAl2O4 and n-type CeO2 heterostructure (CeO2-CoAl2O4) used as an electrolyte exhibits a cell performance of 758 mW/cm2 under fuel cell H2/air conditions at 550 °C, which is quite higher than the pure CoAl2O4 and CeO2 fuel cell devices. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) verified the heterostructure formation including the morphological analysis of the prepared heterostructure composite. The heterostructure-based CeO2-CoAl2O4 composite achieved a higher ionic conductivity of 0.13 S/cm at 550 °C temperature, which means that the constructed device successfully works as an electrolyte by suppressing electronic conductivity. Meanwhile, the obtained results demonstrate the semiconductor ionic heterostructure effect by adjusting the appropriate composition to build heterostructure of the n-type (CeO2) and p-type (CoAl2O4) components and built-in electric field. So, this work exhibits that the constructed device can be effective for energy conversion and storage devices. [ABSTRACT FROM AUTHOR]

The attraction of electronic textiles for next‐generation wearable electronic devices has raised the demands of washable and stretchable energy storage. However, negative effects of washing on the textile‐based devices are majorly known. In this work, besides the innovation of a conventional stretchable composite based on carbon nanotubes (CNT) and polydimethylsiloxane (PDMS) for textile‐based supercapacitors, findings regarding negative and positive effects of washing are introduced. Since the CNT‐and‐PDMS‐based composite (CNT+PDMS) owns high stretchability but low electrochemical performance, two strategies using molybdenum trioxide (MoO3) nanoflakes are designed for upgrading the composite performance. Through stretching, washing, and electrochemical tests, the pros and cons of these strategies are revealed and discussed. Besides, a positive effect of chemical treatment of a liquid detergent (i.e., prewashing) is discovered, and it can improve the prewashed supercapacitor electrodes from 10 to 84 mF cm−2 at a scan rate of 10 mV s−1. Compared to supercapacitor cells assembled from unwashed electrodes, those of the sufficiently prewashed electrodes possess similar stretchability (≈60%) but threefold higher energy and power densities (3.9 μWh cm−2 and 0.89 mW cm−2, respectively). Overall, those findings are beneficial for the development of sustainable e‐textiles for wearable electronic applications. [ABSTRACT FROM AUTHOR]

Combining WO 3 with suitable materials to form heterojunction is essential to overcome the limitations of WO 3 to enhance its photoelectrochemical (PEC) water splitting activity. Moreover, a clear understanding of photo-response and charge behavior of materials could lead to the rational design of efficient photoelectrodes. Given this, an efficient strategy is applied to fabricate WO 3 heterojunction with nitrogen-doped carbon dots (NCDs) and in-depth characterization to investigate the surface charge dynamics using nano imaging in a relation to the enhanced PEC water splitting activity. The optimized NCDs loading to the WO 3 NRs exhibited the enhanced photocurrent density of 1.54 mA cm−2 at 1.23V vs RHE under AM 1.5 G illumination, highest IPCE of ~82 % (at 308.32 nm). The Kelvin probe force microscopy and electrostatic force microscopy reveal that after loading NCDs to the WO 3 , a relatively smooth charge transport has been observed, which improves the PEC. Furthermore, this work demonstrates the effect of photogenerated charges caused by the NCDs that assist in enhancing the increased photocurrent, hydrogen production efficiency, and stability of the PEC water splitting system. Significantly, the nano imaging characterization utilized in this work could be extended to various photoanodes to study the surface charge dynamics. [Display omitted] • WO 3 NRs/NCDs heterojunction was proposed for water splitting applications. • NCD on WO 3 suppresses charge recombination and decreases charge transfer resistance. • Enhanced photocurrent, IPCE, and H 2 production was achieved upon NCD sensitization. • Nanoscale surface imaging was performed to understand insights of carrier dynamics. [ABSTRACT FROM AUTHOR]

The phase control of transition metal dichalcogenides (TMDs) is an intriguing approach for tuning the electronic structure toward extensive applications. In this study, WSe 2 nanosheets synthesized via a colloidal reaction exhibit a phase conversion from semiconducting 2H to metallic 2M under Se-rich growth conditions (i.e., increasing the concentration of Se precursor or lowering the growth temperature). High-resolution scanning transmission electron microscopy images are used to identify the stacking sequence of the 2M phase, which is distinctive from that of the 1T' phase. First-principles calculations employing various Se-rich models (intercalation and substitution) indicated that Se enrichment induces conversion to the 2M phase. The 2M phase WSe 2 nanosheets with the Se excess exhibited enhanced electrocatalytic performance in the hydrogen evolution reaction (HER). In situ X-ray absorption fine structure studies suggested that the excess Se atoms in the 2M phase WSe 2 enhanced the HER catalytic activity, which is supported by the Gibbs free energy (ΔG H* ) of H adsorption and the Fermi abundance function. These results provide an appealing strategy for phase control of TMD catalysts., (© 2023 Wiley-VCH GmbH.)