The development of bifunctional electrocatalysts that simultaneously exhibit high activity and stability in acidic media is crucial for the commercialization of proton exchange membrane water electrolysis. This study addressed the challenges associated with RuO2, such as high reaction barriers, poor stability during the oxygen evolution reaction (OER), and insufficient activity for the hydrogen evolution reaction (HER). We introduced the construction of a RuO2/La2O3 heterostructure, utilizing electron-rich La2O3 as an “electron pump” to modulate the electronic state of RuO2 and stabilize the Ru active sites. Electronic structure analysis confirmed the transfer of 0.2 |e| from La2O3 to RuO2, resulting in an upshift of the Ru d-band center, which optimized the adsorption behavior of reaction intermediates. The optimized catalyst exhibited excellent bifunctional performance in 0.5 M H2SO4, with low overpotentials of 178 mV for OER and 77 mV for HER at 10 mA/cm2, and maintained stable OER operation for over 200 h. This work elucidated the enhancement mechanism of rare-earth oxides acting as electron pumps and provided new insights for designing high-performance acidic electrocatalysts.

Proton exchange membrane water electrolysis (PEMWE) is an environmentally friendly and efficient technology for hydrogen production, playing a vital role in mitigating the fossil energy crisis and bridging renewable energy generation with hydrogen utilization. This work investigates an Ir0.5Ru0.5 nanocluster supported on the nitrogen-vacation-rich niobium nitride (Ir0.5Ru0.5/NbN) for acidic oxygen evolution reaction (OER). Through defect engineering, the electron cloud density of Ir0.5Ru0.5 active sites is precisely modulated, thereby reinforcing strong metal-support interaction (SMSI) at interfaces. Concomitantly, Ir0.5Ru0.5 nanoclusters with high-density grain boundaries induce local charge rearrangement and orbital hybridization for precise d-band center downshift, are fabricated via a doping strategy, thereby accelerating the intrinsic reaction kinetics of OER. The Ir0.5Ru0.5/NbN catalyst exhibits excellent OER performance, achieving a low overpotential of 228 mV at 10 mA cm-2 and high stability, maintaining activity for 700 h without degradation. In addition, it presents outstanding performance as an anode in PEMWE with a cell voltage of 1.79 V at 2 A cm-2. This work provides a viable and efficient approach to reduce Ir loading in PEMWE dramatically, offering a prospective strategy for the cost-effective generation of green hydrogen.

Seawater electrolysis is a promising route for green hydrogen production, yet chloride-induced corrosion and sluggish oxygen evolution reaction (OER) kinetics remain major obstacles. While CeO2 has been widely studied for enhancing OER, most reported CeO2-modified transition metal phosphides (TMPs) still suffer from inadequate current density and insufficient chloride corrosion resistance. Herein, a self-supporting Fe-Ni2P/CeO2/NF electrocatalyst was fabricated via a one-step hydrothermal-phosphidation approach. It requires low overpotentials of 355 mV and 374 mV to achieve 1 A cm-2 in alkaline freshwater and simulated seawater, respectively. The assembled overall water-splitting system demonstrated stable operation for over 200 h in natural seawater at 1 A cm-2. Density functional theory (DFT) calculations reveal that CeO2 induces interfacial charge redistribution, enriches electron density in Fe/Ni2P, and optimizes intermediate adsorption, thereby accelerating OER. Meanwhile, this electronic modulation weakens *Cl binding and suppresses chlorine evolution. This work offers new insights into designing durable and active electrocatalysts for scalable seawater splitting.

Hydrogen is a zero-carbon-emission, high-energy-density energy carrier.

Due to the harsh operating environment under acidic conditions, electrocatalysts are highly susceptible to dissolution, making the search for an OER catalyst suitable for proton exchange membrane (PEM) water electrolysis cells a significant challenge. In this study, we synthesized a polycrystalline IrO2/MnO2 catalyst using an extremely simple one-step hydrothermal method. The carrier-catalyst interactions present during the OER process significantly enhance the intrinsic activity and durability of the Ir-based catalyst, partially resolving the trade-off between catalyst activity and stability. The results reveal an exceptionally low overpotential of only 211 mV at 10 mA cm-2 for IrO2/MnO2 compared to commercial IrO2 catalysts. Furthermore, IrO2/MnO2 exhibits outstanding stability exceeding 1500 h at this potential. This stability is attributed to the strong interaction between IrO2 and the MnO2 substrate, which induces directed electron transfer during the reaction. This mechanism effectively suppresses the overoxidation of Ir sites. In situ characterization techniques were employed to investigate the catalytic reaction pathway. Revealing an AEM mechanism that effectively suppresses lattice oxygen escape, significantly enhancing the catalyst's structural stability. Our work not only aids in improving the design of acidic OER catalysts but also advances the development of low-iridium OER electrocatalysts.

The development of highly active and stable catalysts of oxygen evolution reaction (OER) plays a crucial role in proton-exchange-membrane water electrolysis (PEMWE). Herein, an electronic modulate was used to fabricate oxygen defect-rich and supported metal catalysts AuIr/Nb2O5-x, and it promoted the sluggish kinetics and low efficiencies of OER with the interaction between oxygen defects and the active sites. The Nb-O defect with an electron redistribution and manipulated active electronic state tailored the OER performance. The Ir actively exposed the AuIr/Nb2O5-x-500 catalyst, which exhibited a low overpotential of 230 mV and maintained an excellent stability for 200 h at the current density of 10 mA cm- 2 in 0.5 M H2SO4 electrolyte. Furthermore, the PEMWE using AuIr/Nb2O5-x-500 as the anode revealed a high water-splitting performance (1.61 V @ 0.5 A cm- 2& 1.70 V @ 1 A cm- 2). In-situ Raman spectra and theoretical calculations revealed the electronic structure of AuIr/Nb2O5-x-500 and the mechanism of OER processes, which rationalized the improved performance through the synergistic effect of metal-support interaction and defect effect.

Seawater electrolysis emerges as a promising technology for hydrogen (H2) production, however, the low selectivity of electrocatalysts for oxygen evolution reaction (OER) is a long-standing challenge, which is caused by the chlorine evolution reaction (CER) or hypochlorite formation on the anode, leading to the catalyst corrosion and environmental pollution. Here, the principles of coordination chemistry are proposed, and realized using the FeMn Metal-Organic Framework (MOF) based catalysts for addressing such a challenge. The developed catalysts have the preferential interaction between metal active sites and oxygenated reactants to promote oxygen evolution over chlorine evolution, which ensures a remarkably high selectivity of approximate to 99% toward oxygen evolution in seawater, while suppressing ClER and hypochlorite formation. Furthermore, the FeMn-MOF catalyst demonstrates long-term stability in 500 h of seawater electrolysis tests. The successful operation of FeMn-MOF catalyst in a zero-gap electrolyzer at 300 mA cm-2 and an industrial alkaline seawater electrolyser (ASWE) stack (area 235.5 cm2 anode area in total) at 24 A achieves a new break-through in the decomposition performance of industrial seawater electrolysis.

Controllable preparation of advanced electrocatalysts with well-designed architecture and desirable active sites for rechargeable Zn-air batteries (ZABs) is challenging. Herein, a hollow urchin-like bifunctional oxygen electrocatalyst (HCoPNC@Co/Co2P-PNCNTs) was developed by assembling P, N-doped carbon nanotubes with confined Co/Co2P heterojunctions on heteroatom-doped carbon hollow spheres via in situ polymerization/deposition, pyrolysis and topical phosphorization strategy. According to the analysis of experiments and theoretical calculations, the Co/Co2P@NC core-shell structure at the top of each CNT was verified to facilitate the electron transfer and the conversion between the adsorbed intermediates, guaranteeing outstanding intrinsic catalytic activity. Meanwhile, the urchin-like hierarchical frameworks led to the formation of a desirable conductive and mass transport network, ensuring the efficient exposure of the electrocatalytic active sites and excellent structural stability. Therefore, the "framework-active sites" endowed HCoPNC@Co/Co2P-PNCNTs with superior catalytic activities towards the oxygen reduction reaction (ORR, half-wave potential of 0.83 V) and oxygen evolution reaction (OER, overpotential of 350 mV@10 mA cm-2) in alkaline electrolyte. Expectedly, the as-assembled ZABs based on HCoPNC@Co/Co2P-PNCNTs delivered a large peak power density of 250 mW cm-2 and a robust charge-discharge cycling stability with negligible voltage decay for 110 h at 2 mA cm-2, illustrating its great practical application in advanced metal-air batteries.

The development of electrochemical supercapacitors has attracted a lot of attention in recent years because of the increasing demand for efficient, high-power energy storage. However, SCs' energy storage capacity is still relatively low. Herein, the ternary metal sulfide CoNiCu with an octahedral hollow structure is obtained by introducing Cu2+ with great conductivity and etching with hydrothermal vulcanization. The samples exhibit outstanding performance in the supercapacitor due to the synergistic effect of Co, Cu and Ni. Experimental results prove that its specific capacitance is 2047 F g-1 at 1 A g-1. On the other hand, the supercapacitor device demonstrates a remarkable energy density of 87.8 W h kg-1 when subjected to a power density of 632.0 W kg-1, along with outstanding cycling performance (maintaining 92.86% of its capacity after 20 000 cycles at 10 A g-1). Our work offers a simple hydrothermal vulcanization etching method for synthesizing trimetallic sulfides, which shows good prospects for electrochemical energy storage applications. The trimetallic sulfide with an octahedral hollow structure is a supercapacitor component material with excellent performance.

Water electrolysis is one of the most promising green hydrogen production technologies. However, using precious metal materials as electrodes for these electrolyzers incurs high costs. To address these challenges and simultaneously retain the catalytic activity of precious metals, we synthesize a low-iridium catalyst, Nd-IrO2. 2 . At 10 and-10 mA/cm2, 2 , this catalyst exhibits 233 and 36 mV overpotentials. Nd-IrO2 2 maintains stability over prolonged operation in acidic environments, as evidenced by its consistent overpotential. Advanced calculations using density functional theory (DFT) have demonstrated that incorporating Nd and an ample amount of oxygen vacancies can modulate the d-band center of Ir and reduce the adsorption energy of electrochemical reaction intermediates. In summary, we present the synthesis of a low-iridium catalyst, which provides valuable insights for the design and development of catalysts with improved electrocatalytic performance.

Water electrolysis is one of the most promising green hydrogen production technologies. However, using precious metal materials as electrodes for these electrolyzers incurs high costs. To address these challenges and simultaneously retain the catalytic activity of precious metals, we synthesize a low-iridium catalyst, Nd–IrO2. At 10 and -10 mA/cm2, this catalyst exhibits 233 and 36 mV overpotentials. Nd–IrO2 maintains stability over prolonged operation in acidic environments, as evidenced by its consistent overpotential. Advanced calculations using density functional theory (DFT) have demonstrated that incorporating Nd and an ample amount of oxygen vacancies can modulate the d-band center of Ir and reduce the adsorption energy of electrochemical reaction intermediates. In summary, we present the synthesis of a low-iridium catalyst, which provides valuable insights for the design and development of catalysts with improved electrocatalytic performance.

The design of low-cost and high-performance anodic electrocatalyst is essential in proton exchange membrane water electrolysis (PEMWE) application. Herein, we design and synthesize a core–shell structure with Ir-rich shell and AuIr alloy core by using a simple liquid phase reduction method, which exposed a large number of active sites. The d-band center of Ir active sites, merely 2 nm in size, was shifted by the electronegativity difference between the Au and Ir atoms at the core–shell interface. The strong electronic effect can inhibit the dissolution and corrosion of Ir active sites under acidic and high potential conditions. As a result, Irx@Au0.25Ir0.75−x catalyst shows merely 235 mV overpotential at the current density of 10 mA cm−2, 75 mV lower than the commercial Ir black catalyst, and 2.6-fold higher mass activity than the commercial Ir black catalyst. Furthermore, when Irx@Au0.25Ir0.75−x was used as the anionic catalyst, the electrolysis voltage at 1 A cm−2 is 1.7 V in PEMWE, and this activity was maintained for more than 100 h and had exhibited excellent stability, indicating its ideal prospects as an electrocatalyst. AuIr alloy with Ir-rich core and AuIr alloy shell exposed numerous active sites and improved the utilization efficiency of electrocatalyst.

Proton exchange membrane electrolysis of water is currently recognized in the world as an up-and-coming method for the preparation of green hydrogen energy. Due to its sustainability and low pollution, it has attracted much attention from practitioners recently. The most advanced iridium oxide (IrO2) is the most promising catalyst. However, developing a highly efficient and stable IrO2 catalyst that can adapt to industrial conditions remains a terrific challenge. One of the main problems to be solved is that the slow oxygen evolution reaction(OER) at the anode limits the production of hydrogen. We propose a straightforward method for synthesizing Ce metal-doped IrO2 with a high oxygen vacancy concentration while simultaneously improving the IrO2 catalytic activity and stability. The Ce-doped IrO2 (Ce-IrO2) exhibits a microscopic nanoparticle morphology and a high density of oxygen vacancies, enabling a rapid oxygen evolution reaction (OER) process with a low overpotential of 240 mV at 10 mA & sdot;cm-2 and a remarkable stability of over 50 h under acidic conditions. A growing body of research shows a synergistic effect of oxygen vacancies and mental dopants on the adsorption and evolution of active intermediates in the active center so that the oxygen evolution reaction activity of the Ir-based catalyst can be improved. We hope that our work will provide a sample method for acquiring catalysts capable of adapting to a wide range of conditions via metal doping.

The synthesis of efficient, stable, and green multifunctional electrode materials is a long-standing challenge for modern society in the field of energy storage and conversion. To this end, we successfully synthesized five bimetallic precursor materials with excellent performance by hydrothermal reaction with the assistance of a high concentration of polyvinylpyrrolidone (PVP), and then, sulfide etched the lamellar precursor materials among them to obtain the one-dimensional heterostructured samples. Benefiting from the synergistic effect of the bimetal and the continuous electron/ion transport structure, the samples displayed excellent bifunctional activity in supercapacitor and oxygen evolution reaction (OER). Regarding supercapacitors, the exceptional performance of 2817.2 F g-1 at 1 A g-1 was demonstrated, while the asymmetric supercapacitors made showed an extraordinary energy density of 150.2 Wh kg-1 at a power density of 618.5 W kg-1 and outstanding cycling performance (94.74% capacity retention after 20,000 cycles at 10 A g-1). Simultaneously, a wearable flexible electrode that can be wrapped around a finger was coated on a carbon cloth and was found to light up a 0.5-m-long strip of light. Moreover, it exhibited an ultralow oxygen reduction overpotential of 249 mV at 10 mA cm-2. Hence, our work provides a facile strategy to modulate the synthesis of heterogeneous structured sulfides with a continuous electron/ion transport pathway, which possesses excellent oxygen reduction electrocatalytic performance while meeting superior supercapacitor performance. Such work provides an effective approach for the construction of multifunctional electrochemical energy materials.

Rational designing and exploiting non-noble metal electrocatalysts with desirable nanoarchitecture and abun-dant active sites are crucial but challenging requirements for the development of fuel cells and Zn-air batteries (ZABs). Herein, a highly efficient carbonous hybrid is developed using a facile and effective synthesis strategy via template-assisted and optimized post-pyrolysis processes. The optimized electrocatalyst (denoted as Fe@NC-700) has extremely large specific surface area (1262.8 m2 g-1), and presents a desirable hierarchically porous nano -architecture, including plenty micro-/meso-pores, which endows the catalyst with the enhanced mass transfer for the reaction species. More importantly, Fe@NC-700 possesses not only numerous FeIIN4 moiety uniformly dispersed in N-doped carbon matrix, but also encapsulated Fe/Fe3C nanoparticles, synergistically boosting the electrocatalytic activity towards oxygen reduction reaction (ORR) verified by density functional theory (DFT) calculation. Due to the beneficial microstructure and rich active sites, the catalyst has a positive half-wave po-tential (E1/2) of 0.865 V for ORR in alkaline electrolyte, intrinsic 4e- reaction path and robust stability (only 14 mV negative shift of E1/2 after 10,000 potential cycles), outperforming the Pt/C. Impressively, the aqueous and quasi-solid-state primary ZABs assembled with Fe@NC-700 as cathode catalyst demonstrate superior discharge performance and excellent durability, holding promising potential in practical application of energy conversion devices.

Assembled Co/Mo–MnSe x //AC HBS devices and electrochemical properties.

Bifunctional electrodes with high electrochemical activity for oxygen evolution reaction (OER) and capacitance characteristics are essential for overall water-splitting devices and supercapacitors. Here, the S-etched Co/Mn-metal-organic frameworks (Co/Mn-MOF) derivative (MnCo2O4@Co9S8-10) electrode with dodecahedral hollow heterostructure was prepared by a vulcanization strategy, which greatly improves the bifunctional activity of the electrode. Specifically, the OER requires low overpotentials of 297 and 340 mV to provide current densities of 100 and 500 mA cm(-2), respectively, and it remained stable in alkaline electrolyte for 300 h using a high current cycle test. The activity of the overall water-splitting electrolyzer did not decrease significantly even in alkaline simulated seawater, which means that it has a resistance to chlorine corrosion. In terms of capacitive performance, the MnCo2O4@Co9S8-10 electrode shows a specific capacitance of 1555.43 F g(-1) at 0.5 A g(-1). The assembled MnCo2O4@Co9S8-10//AC battery-supercapacitor hybrid (BSH) has a high energy density of 154.18 W h kg(-1) at 388.69 W kg(-1) power density, and the capacitance retention rate is still as high as 93.4% after 50,000 cycles. The self-assembled flexible solid-state battery successfully lights up the LED board. These results demonstrate the wide applicability of the high-performance bifunctional MnCo2O4@Co9S8-10 electrode in supercapacitors, wearable electronic devices, water splitting, and even seawater electrolysis devices and reveal promising prospects with important implications for energy storage and hydrogen economy.

Sustainable development is the cornerstone of the long-term healthy development of energy and the ecological environment, and a diversified energy system is the frontier technology to respond to sustainable development. The advanced energy systems are not limited to the field of energy storage; the related fields, such as electrocatalysis, are also important energy support systems. The electrocatalytic and energy storage performance of bimetallic metal–organic framework (MOF) is enhanced with the synergistic effect of thioacetamide-induced sulfidation progress, which tunes the crystal structure of bimetallic organic frameworks. The specific capacitance is as high as 1555.43 F g−1 at a current density of 0.5 A g−1. The assembled Co-Mn-S-10//AC BSH exhibits a high energy density of 154.18 Wh kg−1 at a power density of 388.69 W kg−1. The capacitance retention rate is remarkably still as high as 93.43% after 50,000 cycles at a current density of 10 A g−1. Meanwhile, Co-Mn-S-10 exhibits excellent electrocatalytic activity with a low overpotential of 235 mV for the oxygen evolution reaction at a current density of 10 mA cm−2. This paper provides a reference strategy for the preparation of diversified energy materials for electrocatalysis and energy storage.

Rationally tailoring a nonprecious metal and highly active bifunctional catalyst with desirable nanoarchitecture and composition for water electrolysis is of key value for sustainable and clean energy production. Herein, we designed nanoporous N-doped carbon (NC) as a support for dispersion and anchoring of bimetallic phosphide nanoparticles (CoP/Ni2P). Thanks to the uniformly anchored nanosized CoP/Ni2P nanoparticles offering rich active sites and the coupling effect between these nano-particles and a nanoporous NC support to ensure promising conductivity and structural stability, the as-prepared hybrid (CoP(Ni2P)/NC) exhibits prominent electrocatalytic perform-ances toward hydrogen evolution (or oxygen evolution) in alkaline electrolytes, in terms of a small overpotential of 216 mV (or 338 mV) at 10 mA cm-2 and a low Tafel slope of 84 mV dec-1 (or 60 mV dec-1), as well as exceptional long-term stability.

Bimetallic metal-organic framework (MOF) has attracted great interest as an electrode for supercapacitors. Most metal sources are limited to valences of + 2 and + 3. We select metal sources of Co (II) and Mo (VI) and demonstrated a crystalline bimetallic MOF precursor prepared by using a facile chemical synthesis. The one-step solvothermal strategy is assisted by thioacetamide (TAA) for the self-assembly Co-Mo-S nanosheet arrays (Co-Mo-S NSAs). TAA-induced etching is essential to regulate the assembly of amorphous structures. Otherwise, only a single-structure crystalline Co-Mo-S could be obtained. The Co-Mo-S NSAs show a large specific capacitance of 1805.28 F g(-1) at a current density of 0.5 A g(-1). A Co-Mo-S NSAs//AC battery-supercapacitor hybrid (BSH) make with activated carbon as the negative electrode and Co-Mo-S NSAs as the positive electrode. At a current density of 0.5 A g(-1), the BSH shows a high energy density of 169.73 Wh kg(-1) and a power density of 371.44 W kg(-1). After 50,000 cycles, the capacitance retention rate is as high as 94.44%, showing good reversibility and cycle life. This work provides an effective strategy for manufacturing bimetallic MOF-based metal sulfide heterostructure electrode materials for practical energy storage and conversion. (C) 2022 Elsevier B.V. All rights reserved.