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The development of carbon-dioxide-free energy technology using renewable resources has become more urgent due to the continuously increasing global demand for energy. Electrochemical water splitting is a convenient way to produce clean hydrogen fuel. In the present study, we present electrodeposited non-precious mixed-phase Co oxide and Ce oxide heterostructured electrodes as bifunctional electrocatalysts for both oxygen and hydrogen evolution reactions in an alkaline medium. To achieve this, we fabricated various Co1−xCex films (where x = 0.15 and 0.50) by varying the Co/Ce molar ratios of 0.85 : 0.15 and 0.50 : 0.50. The optimized material, referred to as Co0.85Ce0.15, exhibits an ultralow overpotential of 177 mV and 76 mV for the OER and HER, at 20 and −10 mA cm−2, respectively. The overall water splitting (OWS) electrolyzer constructed with optimized electrodes exhibits ultralow cell voltages of 1.56, 2.05, and 2.27 V to achieve current densities of 10, 500, and 1000 mA cm−2 with superbly enhanced electrochemical durability over 40 h at industrially relevant high biases of up to 1000 mA cm−2. Moreover, the OWS further reduced the cell voltage to 1.48 V at an operating temperature of 55 °C, whereas the industrially relevant current density of 1000 mA cm−2 was easily achieved at a cell voltage of only 2.07 V. This work provides new insights for the optimization of multi-metal LDHs by engineering intermediate energy barriers for bifunctional catalysts. [ABSTRACT FROM AUTHOR]

Using electrocatalytic water reduction to produce hydrogen fuel offers significant potential for clean energy, yet its large-scale adoption depends on developing cost-effective, non-precious, and efficient catalysts to replace expensive Pt-based state-of-the-art HER catalysts. The catalytic HER performance of an active catalyst largely depends on the available catalytic active sites, conductivity, and intrinsic electrochemical kinetics, all of which can be altered by incorporating a heteroatom into the active catalyst structure. Herein, we synthesized a unique nitrogen-doped CuO@CuS (NCOS) core–shell-structured catalyst through a facile hydrothermal process followed by an efficacious nitrogenation process, and its electrochemical performance for the HER was systematically analyzed. The NCOS core–shell-structured catalyst exhibits a reduced overpotential (55 mV) and Tafel slope (107 mV dec−1) compared to the pure CuS (CS; 179 mV and 201 mV dec−1) catalyst at a current density of 10 mA cm−2. Moreover, the NCOS core–shell-structured catalyst demonstrates excellent endurance for up to 50 h of chronopotentiometric testing at a driving current density rate of 10 and 100 mA cm−2. This excellent catalytic HER activity is a result of an increased electron transfer rate and a greater number of accessible active sites, attributed to a change in structural properties and the high electronic conductivity aroused from nitrogen incorporation, as evidenced from the TOF and EIS curve analyses. [ABSTRACT FROM AUTHOR]

Silicon belongs to group 14 elements along with carbon, germanium, tin, and lead in the periodic table. Similar to carbon, silicon is capable of forming a wide range of stable compounds, including silicon hydrides, organosilicons, silicic acids, silicon oxides, and silicone polymers. These materials have been used extensively in optoelectronic devices, sensing, catalysis, and biomedical applications. In recent years, silicon compounds have also been shown to be suitable for stabilizing delicate halide perovskite structures. These composite materials are now receiving a lot of interest for their potential use in various real‐world applications. Despite exhibiting outstanding performance in various optoelectronic devices, halide perovskites are susceptible to breakdown in the presence of moisture, oxygen, heat, and UV light. Silicon compounds are thought to be excellent materials for improving both halide perovskite stability and the performance of perovskite‐based optoelectronic devices. In this work, a wide range of silicon compounds that have been used in halide perovskite research and their applications in various fields are discussed. The interfacial stability, structure–property correlations, and various application aspects of perovskite and silicon compounds are also analyzed at the molecular level. This study also explores the developments, difficulties, and potential future directions associated with the synthesis and application of perovskite‐silicon compounds. [ABSTRACT FROM AUTHOR]

The deprived electrochemical kinetics of the oxygen evolution reaction (OER) catalyst is the prime bottleneck and remains the major obstacle in the water electrolysis processes. Herein, a facile hydrothermal technique was implemented to form a freestanding polyhedron-like Co3O4 on the microporous architecture of Ni foam, its reaction kinetics enhanced through sulfide counterpart transformation in the presence of Na2S, and their catalytic OER performances comparatively investigated in 1 M KOH medium. The formed Co3S4 catalyst shows outstanding catalytic OER activity at a current density of 100 mA cm−2 by achieving a relatively low overpotential of 292 mV compared to the pure Co3O4 catalyst and the commercial IrO2 catalyst. This enhancement results from the improved active centers and conductivity, which boost the intrinsic reaction kinetics. Further, the optimized Co3S4 catalyst exhibits admirable prolonged durability up to 72 h at varied current rates with insignificant selectivity decay. The energy dispersive X-ray spectroscopy (EDX) and Raman spectra measured after the prolonged OER stability test reveal a partial transformation of the active catalyst into an oxyhydroxide phase (i.e., CoOOH@Co3S4), which acts as an active catalyst phase during the electrolysis process. [ABSTRACT FROM AUTHOR]

Developing effective and long-lasting electrocatalysts for oxygen evolution reaction (OER) is critical for increasing sustainable hydrogen production. This paper describes the production and characterization of CoFeP nanoparticles (CFP NPs) as high-performance electrocatalysts for OER. The CFP NPs were produced using a simple hydrothermal technique followed by phosphorization, yielding an amorphous/crystalline composite structure with improved electrochemical characteristics. Our results reveal that CFP NPs have a surprisingly low overpotential of 284 mV at a current density of 100 mA cm−2, greatly exceeding the precursor CoFe oxide/hydroxide (CFO NPs) and the commercial RuO2 catalyst. Furthermore, CFP NPs demonstrate exceptional stability, retaining a constant performance after 70 h of continuous operation. Post-OER characterization analysis revealed transformations in the catalyst, including the formation of cobalt–iron oxides/oxyhydroxides. Despite these changes, CFP NPs showed superior long-term stability compared to native metal oxides/oxyhydroxides, likely due to enhanced surface roughness and increased active sites. This study proposes a viable strategy for designing low-cost, non-precious metal-based OER catalysts, which will help advance sustainable energy technology. [ABSTRACT FROM AUTHOR]

Water electrolysis is a highly efficient route to produce ideally clean H2 fuel with excellent energy conversion efficiency and high gravimetric energy density, without producing carbon traces, unlike steam methane reforming, and it resolves the issues of environmental contamination via replacing the conventional fossil fuel. Particular importance lies in the advancement of highly effective non-precious catalysts for the oxygen evolution reaction (OER). The electrocatalytic activity of an active catalyst mainly depends on the material conductivity, accessible catalytically active sites, and intrinsic OER reaction kinetics, which can be tuned via introducing N heteroatoms in the catalyst structure. Herein, the efficacious nitrogenation of CuS was accomplished, synthesized using a hydrothermal procedure, and characterized for its electrocatalytic activity towards OER. The nitrogen-doped CuO@CuS (N,CuO@CuS) electrocatalyst exhibited superior OER activity compared to pristine CuS (268 and 602 mV), achieving a low overpotential of 240 and 392 mV at a current density of 10 and 100 mA/cm2, respectively, ascribed to the favorable electronic structural modification triggered by nitrogen incorporation. The N,CuO@CuS also exhibits excellent endurance under varied current rates and a static potential response over 25 h with stability measured at 10 and 100 mA/cm2. [ABSTRACT FROM AUTHOR]

Nanocrystals of CsPbBr3, a colloidal perovskite, are hybridized with silver nanoparticles (Ag NPs) and organic molecules (2,5‐diphenyloxazole, PPO) to improve X‐ray radioluminescence (RL). It is known that charge transfer from the PPO molecules to the CsPbBr3 nanocrystals enhances the RL efficiency of the CsPbBr3 nanocrystals. In this study, Ag NPs are introduced to further enhance the RL efficiency. The plasmonic process of the Ag NPs is activated by the PPO molecules, which contain X‐ray‐induced high‐energy charges. Subsequently, electric fields induced by the plasmonic process of the Ag NPs accelerate the charge transfer from the PPO molecules to the CsPbBr3 nanocrystals. The plasmonic effect of the Ag NPs is demonstrated by the full‐width half maximum (FWHM): the photoluminescence FWHM of the hybridized CsPbBr3 nanocrystals is reduced, whereas the RL FWHM remains unchanged. The Ag‐NP‐induced plasmonic effect improves the RL efficiency of the PPO‐decorated CsPbBr3 nanocrystals by ≈10%. The obtained results demonstrate that a plasmonic process can strengthen the RL of X‐ray scintillators for X‐ray detection and imaging. [ABSTRACT FROM AUTHOR]

Because hydrogen is an ideal energy source, electrocatalysts for water splitting that employ transition metal hydroxides rather than expensive precious metals to produce molecular hydrogen have been extensively investigated. In the present study, NixFeyMoz layered double hydroxide (LDH) electrocatalysts fabricated via a simple hydrothermal technique for overall water splitting in an alkaline medium are reported. The best-performing NixFeyMoz LDH catalysts require overpotentials of 200 and 86 mV to reach a current density of 10 mA cm−2 for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. Theoretical analysis indicates that the Mo-rich OMo2Fe and Fe-rich OFe3 active sites strongly activate the HER and OER, respectively. More importantly, a water electrolyzer containing the best-performing NixFeyMoz LDH catalysts as the anode and cathode is able to reach an industrially relevant current density of 1000 mA cm−2 at a cell voltage of only 2.1 V. The electrolyzer exhibits outstanding stability at very high current densities of 0.1, 0.5 and 1 A cm−2 for overall water splitting over 90 hours of continuous operation, which is superior to state-of-the-art devices based on precious metals. The overall water-splitting activity presented here demonstrates the practical potential of the proposed electrocatalysts as inexpensive options for use in water electrolyzers. [ABSTRACT FROM AUTHOR]

Green hydrogen derived from the water-electrolysis route is emerging as a game changer for achieving global carbon neutrality. Economically producing hydrogen through water electrolysis, however, requires the development of low-cost and highly efficient electrocatalysts via scalable synthetic strategies. Herein, this work reports a simple and scalable immersion synthetic strategy to deposit reduced graphene oxide (rGO) nanosheets integrated with Ni–Fe-based hydroxide nanocatalysts on nickel foam (NF) at room temperature. As a result of synergetic interactions among the hydroxides, rGO and NF, enhanced catalytic sites with improved charge transport between the electrode and electrolyte were perceived, resulting in significantly enhanced oxygen evolution reaction (OER) activity with low overpotentials of 270 and 320 mV at 100 and 500 mA cm−2, respectively, in a 1.0 M KOH aqueous electrolyte. This performance is superior to those of the hydroxide-based electrode without incorporating rGO and the IrO2-benchmark electrode. Furthermore, when the conventional OER is substituted with urea decomposition (UOR) as a proxy anodic reaction, the electrolyzer achieves 100 and 500 mA cm−2 at a lower potential by 150 and 120 mV, respectively than the OER counterpart without influencing the hydrogen evolution reaction (HER) activity at the cathode. Notably, the rGO-incorporated electrode delivers a spectacularly high UOR current density of 1600 mA cm−2 at 1.53 V vs. RHE, indicating the decomposition of urea at an outstandingly high rate. [ABSTRACT FROM AUTHOR]

Development of cost-effective and highly efficient electrocatalysts for water splitting is crucial to produce affordable and sustainable green-hydrogen energy that can alleviate the current overreliance on fossil fuels. This work demonstrates the simple immersion-based chemical etching of nickel foam (NF) in an ethanolic FeCl3 solution to generate microporous nickel (Ni) backbones decorated with hierarchically structured metallic Fe doped Ni–Fe-hydroxide nanoparticles serving as a highly promising oxygen evolution reaction (OER) electrode in alkaline water. The optimally etched NF-based OER electrode exhibits a low Tafel slope of 47.3 mV dec−1 and a low overpotential of 220, 270, and 310 mV at 10, 100, and 500 mA cm−2, respectively. Intriguingly, this electrode also exhibits a perfectly reversible OER and HER performance between +400 and −40 mA cm−2 with no evidence of electrode potential decay for 80 h. Importantly, when used with an industrial-type 30 wt% KOH aqueous electrolyte and compared to a benchmark Pt/C(20wt%)‖IrO2-based cell, the electrolyzer exhibits a lower cell voltage of 1.52 (vs. 1.56 V of Pt/C(20wt%)‖IrO2-cell), 1.62 (vs. 1.79), 1.69 (vs. 1.92) and 1.79 (vs. 2.08) V at 10, 50, 100, and 240 mA cm−2, respectively, with the cell voltage maintained for ∼100 h. [ABSTRACT FROM AUTHOR]

Summary: We report an effective strategy generally applicable towards improving Li‐ion battery performance with insulating metal oxide‐based anode materials. We fabricated density‐modulated multilayered homo‐junction tungsten oxide (WOx) films as anode materials for Li‐ion batteries, in which high‐ and low‐density thin layers were alternately deposited on Cu current collectors using radio frequency magnetron sputtering. The performance of the battery with multilayered WOx was systematically optimized by changing the number of layers and deposition order. A 4‐layer density‐modulated WOx anode with a low density on top WOx layer showed superior performance with a high reversible capacity of 508 mAh g−1 after 200 cycles at a current density of 0.2 A g−1. Moreover, it provided a reversible capacity of 150 mAh g−1 and good coulombic efficiency of 93.7% after 1000 cycles at a high current density of 2 A g−1 and showed excellent rate capability and cycling stability. The observed outstanding battery performance of the density‐modulated multilayer WOx anode can be attributed to its controlled mass loading, optimized charge‐transfer kinetics, and favourable morphology. [ABSTRACT FROM AUTHOR]