Bifunctional Electrocatalytic Performance Research Articles

Operando Electro-Oxidation Reconstitution of a Newly Designed 2D Co(II)-MOF on Nickel Foam to Cobalt Oxyhydroxide Nanosheets towards Energy Sustainability: A Holy Grail in Electrocatalytic Water Splitting.

The upsurging of cost-effective de novo electrocatalysts through the operando electro-oxidation approaches holds great promise for the scalable production of green energy in the pursuit of energy sustainability. This work introduces an operando electro-oxidation reconstitution strategy in producing a smart electrocatalyst, cobalt "oxyhydroxide" derived from a newly designed 2D cobalt(II) metal-organic framework (NBU-4) directly grown on nickel foam (NF), NBU-4/NF@CoOOH. The electrocatalyst, NBU-4/NF@CoOOH, exhibits an outstanding overpotential of 76 mV for the hydrogen evolution reaction and 336 mV for the oxygen evolution reaction to achieve a current density of 10 mA/cm2 with remarkable Faradaic efficiencies of 97.1 and 93.4%, respectively, in 1 M aqueous KOH. Unveiling the bifunctionality of NBU-4/NF@CoOOH as the cathode and anode for overall water splitting in 1 M aqueous KOH, a low voltage of 1.65 V was needed to obtain 10 mA/cm2 current density. Nonetheless, NBU-4/NF@CoOOH displayed excellent stability for 12 h as evidenced from the chronopotentiometry recorded at 10 mA/cm2. The outstanding bifunctional electrocatalytic performance and stability of the electrocatalyst for 50 h is attributed to the unique 2D hexagonal nanosheet morphology of NBU-4/NF@CoOOH and the microporous structure with zigzag flow channels of NF, facilitating a faster kinetics through the Co3+ and Ni2+ dual sites synergism.

Bifunctional electrocatalytic performance of MgAlCe-LDH/β-Ni(OH)2/Ni foam in total natural seawater splitting.

Electrocatalytic seawater splitting is a potential solution to environmental problems, as seawater is a plentiful supply of hydrogen sources in nature. Hence, the development of bifunctional electrodes exhibiting outstanding performance in both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is essential for the efficacy of total seawater splitting. Herein, we employed a straightforward method for in situ creation of β-Ni(OH)2 on Ni foam, followed by a hydrothermal approach to manufacture MgAlCe-LDH on β-Ni(OH)2/Ni foam. The linear sweep voltammetry (LSV) experiments demonstrate that the MgAlCe-LDH/β-Ni(OH)2/Ni foam exhibits superior performance for both the OER and the HER in a natural seawater electrolyte compared to the MgAlCe-LDH/Ni foam, β-Ni(OH)2/Ni foam, and Ni foam. Consequently, the MgAlCe-LDH/β-Ni(OH)2/Ni foam requires an 80mV overpotential for OER and 337mV for HER to attain a current density of 10mAcm-2. The enhanced electrocatalytic activity of MgAlCe-LDH/β-Ni(OH)2/Ni foam can be attributed to boosting exposed active sites, improving electronic interaction, and increasing charge transfer capacity resulting from the synthesis of MgAlCe-LDH on β-Ni(OH)2/Ni foam. Implementing a two-electrode configuration for the MgAlCe-LDH/β-Ni(OH)2/Ni foam, the total seawater splitting investigation exhibits 1.42V cell voltage at a current density of 10mAcm-2 and 25h long-term stability.

Combined Exsolution and Electrodeposition Strategy for Enhancing Electrocatalytic Activity of Ti-Based Perovskite Oxides in Oxygen and Hydrogen Evolution Reactions.

The significant interest in perovskite oxides stems from their compositional and structural flexibility, particularly in the field of electrochemistry. In this study, the double E strategy (exsolution and electrodeposition strategies) is successfully devised for synthesizing perovskite-based bifunctional electrocatalysts, enabling simultaneous OER and HER applications with exceptional catalytic performance. The synthesized R-LCTFe/Ni catalyst exhibits outstanding electrocatalytic activity, delivering low overpotentials of 349 and 309mV at 10mA cm-2 for OER and HER, respectively, indicating substantial improvements in the inherent electrocatalytic activity. Moreover, the impressive stability of R-LCTFe/Ni under alkaline conditions underscores its potential for practical water electrolysis applications. The superior bifunctional electrocatalytic performance can be attributed to the reduced charge transfer resistance and the synergistic cooperation between exsolved Fe nanoparticles and electrodeposited Ni compounds. The successful development of the R-LCTFe/Co catalyst further confirms the transferability of the double E strategy. Compared to R-LCTFe/Ni, the overpotential of R-LCTFe/Co is 58mV higher for OER, yet 48mV lower for HER at a current density of 10mA cm-2. This study provides an efficient and promising approach for the fabrication of highly active perovskite-based electrocatalysts, contributing valuable insights into the design of bifunctional electrocatalysts for OER and HER.

Three-dimensional nanoflower-like transition metal sulfide heterostructures (Co9S8/Co1-xS /WS2) as efficient bifunctional oxygen electrocatalysts for Zn-air batteries

The charging and discharging processes of rechargeable Zn-air batteries (ZABs) require the use of precious metal catalysts (Pt and RuO2) that are expensive. Therefore, preparing efficient, stable, and affordable metal bifunctional oxygen electrocatalysts compatible with both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial. Herein, a nanoflower-like Co9S8/Co1-xS/WS2 bifunctional oxygen electrocatalyst with a layered structure has been prepared. The cobalt sulfide serves as the main active site and the synergistic interaction between the multi-components modulates the electronic structure of the active site and generates abundant S vacancies, thereby effectively improving the bifunctional oxygen electrocatalytic performance. The electrocatalytic activity of the prepared catalyst for ORR/OER is close to that of commercial noble metal catalysts. When Co9S8/Co1-xS/WS2 is used as the cathode material in Zn-air batteries, the batteries exhibit high specific capacity (822.6 mAh gZn−1), excellent energy density (958.9 Wh kgZn−1), as well as a battery charge/discharge cycling time that was twice that of the commercial catalyst PtC+RuO2.

MnCo2O4 Nanostructure Anchored on Functionalized Carbon Black for the Enhanced Bifunctional Electrocatalytic Performance of OER and HER.

The electrocatalytic oxygen and hydrogen evolution reactions (OER and HER) are key processes used in energy storage and conversion. We have developed a highly efficient MnCo2O4 nanostructure anchored with functionalized carbon black (MnCo2O4/f-CB), which has been characterized by XRD, FT-IR, Raman spectra, FE-SEM, and HR-TEM analyses as robust bifunctional electrocatalysts for both HER and OER. At a characteristic 10 mA cm-2 current density, the MnCo2O4/f-CB composite ECs exhibit low overpotentials of 330 mV for OER and 360 mV for HER, respectively. Furthermore, the MnCo2O4/f-CB composite ECs exhibit superior current density, the shortest Tafel slope, and admirable durable stability in OER and HER together. Due to the supported f-CB, the MnCo2O4 composite catalyst has more active sites, effective charge transfer, and longer durability. A high-efficiency dual electrocatalyst can be developed from these highly efficient and dual ECs, which are comparable to standard noble metal-based catalysts. The synergetic coupling effects of high-activity f-CB and MnCo2O4 composites with appropriate morphologies are critical factors for the enhanced catalytic performances of the MnCo2O4/f-CB composite.

MXene-supported 2D bimetallic chalcogenide electrocatalyst: Enhanced electrochemical seawater splitting

Hydrogen energy holds immense potential for revolutionizing modern energy technologies. Seawater electrolysis is a promising strategy for hydrogen production; however, the lack of effective electrodes limits its widespread application. Therefore, developing high-performance, cost-effective catalysts for water splitting is essential for sustainable energy conversion. In this context, we report a novel hybrid bimetallic selenide (CoMoSe2) and MXene (Ti3C2Tx) electrocatalyst, which exhibits remarkable catalytic performance for seawater electrolysis. The CoMoSe2@Ti3C2Tx electrocatalyst demonstrates outstanding catalytic capabilities, achieving overpotentials of 82 mV for hydrogen evolution reaction (HER) and 329 mV for oxygen evolution reaction (OER) at a current density of 10 mA cm⁻2 in alkaline conditions. The Tafel slope values are 124 mV dec⁻1 for hydrogen evolution and 69 mV dec⁻1 for oxygen evolution, outperforming their individual components. The enhanced bifunctional catalytic performance of the hybrid catalyst is attributed to the synergistic effect of Mo atoms within the CoSe2 crystal structure, which modifies the electronic structure and lowers the chemisorption energies of hydrogen and oxygen intermediates. The abundance of oxygen vacancies provides more reactive active sites and improves electrical conductivity. Additionally, the CoMoSe2@Ti3C2Tx composite has demonstrated remarkable bifunctional electrocatalytic performance for seawater splitting, achieving 10 mA cm⁻2 at overpotentials of 161 mV for HER and 354 mV for OER in alkaline seawater. The Volmer-Heyrovsky mechanism drives the remarkable long-term stability of the catalyst. This novel approach contributes to sustainable energy solutions by providing a fresh avenue for the development of effective catalysts to produce hydrogen from seawater.

FeCo Bimetallic ZIF Derivatives Decorated with CoFe-LDH to Promote Bifunctional Oxygen Electrocatalysis Activation.

Reasonably screening the targeted oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) constituents and constructing high-efficiency and stabilized ORR/OER bifunctional electrocatalysts are pivotal for the advancement of rechargeable zinc-air batteries (ZABs). Here, CoFe layered double hydroxide (CoFe-LDH) nanosheets are deposited on nitrogen-doped graphite-carbon polyhedra with FeCo alloy nanoparticles (FeCo/LDH-NGCP). Due to the synergic effect between FeCo-NGCP, CoFe-LDH and FeCo/LDH-NGCP, the electrocatalyst with the abundant and accessible active sites can provide good charge/mass transfer, and thus shows wonderful ORR and OER bifunctional electrocatalytic performance. In ORR tests, FeCo/LDH-NGCP catalyst displays larger half-wave potential (E1/2, 0.89 V vs. 0.85 V), higher limiting current density (JL, 5.91 mA/cm2 vs. 5.14 mA/cm2) and better stability than commercial Pt/C. As for OER, FeCo/LDH-NGCP possesses a smaller overpotential (η) of 299.6 mV at a current density of 10 mA/cm2 and more durable stability than commercial RuO2 (330.6 mV). Furthermore, in ZAB tests, the cycling stability of ZAB-FeCo/LDH-NGCP (over 470 h) outperforms the ZAB-Pt/C+RuO2 (92 h) with commercial electrocatalyst (Pt/C+RuO2). Therefore, the FeCo/LDH-NGCP catalyst offers a new perspective to construct ZABs bifunctional catalysts and their commercial application in ZABs.

Se-Doped CoS2@MoS2 Heterostructures on Multiwalled Carbon Nanotubes as Efficient Bifunctional Electrocatalysts for Alkaline Overall Water Splitting.

The use of efficient and affordable non-precious metal catalysts for hydrogen and oxygen evolution reactions is vital for replacing and widely implementing new energy sources. Nevertheless, improving the catalytic performance of these non-precious-metal bifunctional electrocatalysts continues to be a major challenge. In this article, an optimized Se-incorporated bulk CoS2@MoS2 heterostructure grown on the surface of carbon nanotubes is reported. The resulting Se-CoS2@MoS2/CNTs exhibit robust bifunctional electrocatalytic performance, with low overpotentials of 85 and 240mV @ 10 mA·cm-2 for HER and OER, respectively. The materials exhibit superior long-term stability of over 145h, surpassing most electrocatalysts of similar type. This enhanced performance is attributed to the synergistic effect at the interface between the MoS2 and CoS2 phases, abundant active sites, and high active surface area, which collectively improves the electron-transfer efficiency during the reaction process. Furthermore, the incorporation of the amorphous state of Se into the heterostructure yields a change in the crystallinity of the heterostructure in the electronic structure, which optimizes the adsorption and activation energy barriers of the catalytic intermediate. This study thus presents a promising approach to regulating anion doping in bifunctional electrocatalysts.

Bamboo-derived aerogel with atomically dispersed Co as a high-performance bifunctional electrocatalyst for durable zinc-air batteries

The development of highly efficient and durable bifunctional electrocatalysts is crucial for rechargeable zinc-air batteries, which have garnered significant attention as a promising sustainable energy storage technology. Herein, a novel Co-N-C-1050 catalyst is synthesized using a high-temperature gas transport method, where high purity cobalt powder and bamboo biomass aerogel are treated with ammonia gas at 1050 °C. The resulting catalyst exhibits a 3D interconnected porous network composed of dense carbon fibers, which atomically dispersed Co, N, and C elements are uniformly distributed. The synergistic integration of highly active Co single atoms and N-doped 3D carbon fiber aerogel enables Co-N-C-1050 to demonstrate excellent bifunctional electrocatalytic performance for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), comparable to commercial Pt/C and RuO2 catalysts. This catalyst has a half-wave potential of 0.842 V for ORR and a potential of 1.472 V at 10 mA cm−2 for OER, outperforming N-C-1050 and benchmark catalysts. A zinc-air battery is driven by Co-N-C-1050 achieves a high power density of 135 mW/cm2 and exceptional stability over 138 h of charge/discharge cycling, surpassing the higher-cost Pt/C + RuO2 catalyst. This biomass aerogel based single-site Co-N-C catalyst offers a promising approach for developing high-efficiency and long-cycle-life zinc-air batteries.

Regional banks, financing constraints and manufacturing enterprises' total factor productivity: A quasi-natural experiment of China's city commercial banks

The literature shows that the financial system dominated by large national banks restricts enterprises' financing channels, leading to efficiency losses. In response, governments introduce different types of banks to address this issue. However, the literature overlooks the relationships among regional banks, financing constraints and manufacturing enterprises' productivity. We fill this gap by exploiting the China's unique policy of staggered rollout of city commercial banks across cities and using data from Chinese listed manufacturing enterprises over the period 1992 to 2022 to explore how regional banks affect productivity. We find that regional banks represented by city commercial banks in China significantly increase the manufacturing enterprises' total factor productivity by alleviating financing constraints, especially pronounced for state-owned enterprises, large enterprises, and well-established enterprises. Our research results emphasize the effectiveness of regional banks in promoting the development of the manufacturing industry and offer insights for sustainable economic development policies.

Atomic-level structural engineering of La-doped CoMoP composite for enhanced overall water splitting

A series of La-doped CoMoP composites were fabricated through an in-situ phosphorization strategy with La–CoMo layered double hydroxide (LDH) as precursors. The homogenous dispersion of metal ions within the LDH structure facilitated the creation of a uniformly atomic-level La-doped CoMoP composite. Among these, the 5 % La-doped CoMoP exhibited the best performance, requiring only 41 mV overpotential for hydrogen evolution reaction (HER) and 303 mV for oxygen evolution reaction (OER) to reach a current density of 10 mA cm−2. For overall water splitting, it achieved a current density of 10 mA cm−2 at a cell voltage of just 1.61 V and maintained a stable performance over 24 h. The modulation effect of rare-earth elements, combined with the synergistic interactions among transition metal ions, contributes to its excellent bifunctional electrocatalytic performance.

The Asymmetrical Fe-O-Se Bonds in Fe2O(SeO3)2 Boosting Bifunctional Oxygen Electrocatalytic Performance for Zinc-Air Battery.

Zinc-air batteries (ZABs) have the advantages of high energy density and rich zinc raw materials. It is a low-cost, green and sustainable energy storage device. At present, one of the key technologies that hinder the large-scale application of ZABs is the design and fabrication oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) bifunctional catalysts with excellent performance, especially the non-platinum-based catalysts. Here N-doped carbon-coated Fe-based selenium oxide catalyst Fe2O(SeO3)2/Fe3C@NC with high performance has been fabricated by a one-step pyrolysis and then the electrochemical oxidization. The experimental results confirmed that the existence of Fe-O-Se bonds in Fe2O(SeO3)2 crystal phase of Fe2O(SeO3)2/Fe3C@NC, and the Fe-O-Se bonds could obviously enhance ORR and OER catalytic performance of Fe2O(SeO3)2/Fe3C@NC. Density functional theoretical calculations (DFT) confirmed that the Fe2O(SeO3)2 in Fe2O(SeO3)2/Fe3C@NC had a higher d-band center of Fe atom and a lower p-orbital coupling degree with its own lattice O atom than Fe2O3, which leads to Fe site of Fe2O(SeO3)2 being more likely to adsorb external oxygen intermediates. The Fe-O-Se bonds in Fe2O(SeO3)2 results in the modification of coordination environment of Fe atoms and optimizes the adsorption energy of Fe site for oxygen intermediates. Compared with Fe2O3/Fe3C@NC, the Fe2O(SeO3)2/Fe3C@NC showed the obvious enhancements of ORR/OER catalytic activities with a half-wave potential of 0.91 V for ORR in 0.1 M KOH electrolyte and a low overpotential of 345 mV for OER at 10 mA cm-2 in a 1.0 M KOH electrolyte. The peak power density and specific capacity of Fe2O(SeO3)2/Fe3C@NC-based ZABs are higher than those of Pt/C+RuO2-ZABs. The above results demonstrate that the asymmetrical Fe-O-Se bonds in Fe2O(SeO3)2 plays a key role in improving the bifunctional catalytic activities of ORR/OER for ZABs.

Bifunctional Electrocatalyst Enhanced Synergistically by MoS2/Ni3S2 Heterojunctions and Au Nanoparticles for Large‐Current‐Density Overall Water Splitting

AbstractDeveloping transition metal based overall water splitting (OWS) electrocatalysts with high efficiency, low‐cost, large current density, and long‐term stability is crucial for industrial electrolysis of water, but remains a major challenge. In this study, a hierarchical electrocatalyst with MoS2/Ni3S2 heterojunctions and a tiny amount of Au nanoparticles grown on nickel foam (MoS2/Ni3S2‐Au@NF) has been developed by a one‐step hydrothermal method. The heterojunctions and Au nanoparticle decoration induce the electron‐rich interfaces in the catalyst, which facilitate the synergistic adsorption of both OER and HER intermediates. As a result, MoS2/Ni3S2‐Au@NF possesses an excellent bifunctional electrocatalytic performance in 1 M KOH with low HER overpotential (78 mV@10 mA cm−2, 253 mV@500 mA cm−2), low OER overpotential (261 mV@50 mA cm−2, 435 mV@500 mA cm−2), and outstanding cyclical stability and continuous stability, which are superior than typical benchmarks of Pt/C and RuO2. An electrolyzer assembled with the self‐supported MoS2/Ni3S2‐Au@NF electrode also displays excellent OWS activity and stability with a current density beyond 100 mA cm−2. This experiment is responding a potential alternative non‐precious metal electrocatalyst for OWS at industrial settings, and thus promotes the real‐world application of hydrogen energy conversions.

Development of an efficient bifunctional electrocatalyst based on Co/CoSe2 nanoparticles embedded in N, Se co-doped carbon for AEMFC and rechargeable Zn-air battery

We suggest a hollow-structured N, Se dual-doped carbon framework embedded with Co/CoSe2 nanoparticles (Co/CoSe2@NSeC) as highly efficient bifunctional electrocatalyst for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The prepared electrocatalyst exhibits high electrochemical active surface area attributed to its unique hollow/porous structure and defective heteroatom doping sites. Furthermore, the strongly coupled heterojunction between Co and CoSe2 species not only provides abundant and highly active sites but also generates built-in electric field, thereby promoting electron transfer during the electrocatalytic reaction. Based on the above considerations, the prepared catalyst shows excellent bifunctional electrocatalytic performance. Leveraging the excellent ORR activity of Co/CoSe2@NSeC, alkaline exchange membrane fuel cells (AEMFC) with the Co/CoSe2@NSeC as air cathode exhibits high power density of 171.23 mW cm2. Furthermore, the rechargeable Zn-air battery employing the Co/CoSe2@NSeC shows high specific capacity (729.4 mAh gZn−1), peak power density (192.88 mW cm2), and sustained stability over 300 cycles.

Co2P/CoP embedded in N, P, S triply-doped hollow carbon towards enhanced oxygen electrocatalysis

Simultaneously dispersing phosphide crystallites and multiple heteroatoms in hollow carbon is a significant yet challenging task for achieving high-performance oxygen electrocatalysts of zinc-air batteries. Herein, a simple wrapping-pyrolysis strategy is proposed to prepare Co2P/CoP embedded in N, P, S triply-doped hollow carbon (Co2P/CoP@NPS-HC). Co2P/CoP@NPS-HC composite features hollow polyhedral structure populated with numerous catalytically active Co2P/CoP nanoparticles and N, P, S heteroatoms. This optimized catalyst exhibits excellent activity for oxygen reduction reaction, with a half-wave potential of 0.82 V vs. RHE, and impressive enhancement for oxygen evolution reaction, indicated by an overpotential of 400 mV at 10 mA cm−2. Moreover, Co2P/CoP@NPS-HC catalyst exhibits greater durability and superior methanol tolerance compared to commercial Pt/C. The excellent bifunctional electrocatalytic performance of Co2P/CoP@NPS-HC catalyst is attributed to the synergistic effect of uniformly dispersed Co2P/CoP nanoparticles and N, P, S triply-doped hollow carbon structure. The former provides abundant catalytically active sites, while the latter offers a high accessible specific surface area, as well as enhances catalytic activity and electronic conductivity due to its altered charge distribution.

Free-standing FeNiCuCoBMo high-entropy alloy bifunctional electrocatalysts for efficient pH-universal water electrolysis

Utilizing the synergistic effects of multi-components has been proven to be a feasible approach to enhance water splitting electrocatalytic activity, since developing efficient and stable bifunctional electrocatalysts within a wide pH range remains a significant challenge. Herein, we report a FeNiCuCoBMo high-entropy alloy (HEA) prepared by dealloying, showing outstanding bifunctional electrocatalytic performance for HER and OER in a pH-universal electrolyte. After dealloying for 7 h, the HER and OER overpotentials of the HEA strips in 1.0 M KOH decreased by 22 mV and 25 mV, respectively.Impressively, the free-standing strips with the optimal compositions achieve low HER (82 mV in acid and 101 mV in alkali at 10 mA·cm−2) and OER (311 mV in acid and 245 mV in alkali at 10 mA·cm−2) overpotentials. In a full hydrolysis experiment, a current of 10 mA·cm−2 can run for 100 h with only 1.58 V, which is attributed to the ample exposure of highly active sites resulting from the synergistic effect of each element. Theoretical calculations further support these findings, showing that the electronegativity differences of the metallic elements in FeNiCuCoBMo result in abnormal activity at specific locations (Fe and Mo).Additionally, charge rearrangement and enhanced electronic conduction at the interface reduce the activation energy barrier, thereby improving the performance of the electrocatalysts.

Synergy of Interface Coupling and Sulfur Vacancies in Ni3S2/Fe2P for Water Splitting.

Integrated application of interface engineering and vacancy engineering is a promising and effective strategy for the design and fabrication of high-performance electrocatalysts. Herein, the heterointerface catalyst with rich sulfur vacancies, vs-Ni3S2/Fe2P, was successfully designed and constructed. The strong heterointerface coupling and rich sulfur vacancies in vs-Ni3S2/Fe2P significantly optimize the electronic structure of the catalyst and synergistically improve the inherent catalytic activity. Benefiting from the optimization of the electronic structure, vs-Ni3S2/Fe2P exhibits excellent bifunctional electrocatalytic performance in alkaline electrolytes. The overpotentials for hydrogen and oxygen evolution reactions (HER and OER) are 99 and 169 mV at a current density of 10 mA cm-2, respectively. Particularly, it achieves an ultrahigh OER performance with an overpotential of 251 mV at 300 mA cm-2. Moreover, the catalyst also displays outstanding long-term durability. Density functional theory (DFT) computations reveal that the synergy of interface coupling and sulfur vacancies is crucial to optimizing the electronic structure. This study offers a hopeful pathway for the design and construction of durable and efficient electrocatalysts.

In-situ building of multiscale porous NiFeZn/NiZn-Ni heterojunction for superior overall water splitting

The development of efficient nonprecious bifunctional electrocatalysts for water electrolysis is crucial to enhance the sluggish kinetics of the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). A self-supporting, multiscale porous NiFeZn/NiZn-Ni catalyst with a triple interface heterojunction on nickel foam (NF) (NiFeZn/NiZn-Ni/NF) was in-situ fabricated using an electroplating−annealing−etching strategy. The unique multi- interface engineering and three-dimensional porous scaffold significantly modify the mass transport and electron interaction, resulting in superior bifunctional electrocatalytic performance for water splitting. The NiFeZn/NiZn-Ni/NF catalyst demonstrates low overpotentials of 187 mV for HER and 320 mV for OER at a current density of 600 mA/cm², along with high durability over 150 h in alkaline solution. Furthermore, an electrolytic cell assembled with NiFeZn/NiZn-Ni/NF as both the cathode and anode achieves the current densities of 600 and 1000 mA/cm2 at cell voltages of 1.796 and 1.901 V, respectively, maintaining the high stability at 50 mA/cm2 for over 100 h. These findings highlight the potential of NiFeZn/NiZn-Ni/NF as a cost-effective and highly efficient bifunctional electrocatalyst for overall water splitting.

One-step corrosion inducing the amorphous/crystalline-Co0.8Ru0.2/RuCoOx heterostructures for urea-assisted water decomposition at ampere-level current density

It is challenging to directionally construct the amorphous/crystalline (a/c)-alloy/oxide heterostructures with exceptional bifunctional electrocatalytic performances via a facile method. With these in mind, the a/c-RuCo NWs/NF electrode with the unique hollow structure and a/c-Co0.8Ru0.2/RuCoOx heterostructure was constructed by cleverly controlling the corrosion time. As expected, the well-designed a/c-RuCo NWs/NF||a/c-RuCo NWs/NF only needs 1.46 V to reach an industrial-grade current density of 1 A cm−2, outperforming other advanced electrodes. Strikingly, density functional theory (DFT) and in-situ Raman reveal that the Ruδ+-Ru0 dual-sites and Coδ+ at the a/c-Co0.8Ru0.2/RuCoOx heterointerface act as active species for alkaline HER and UOR, synergistically promoting urea-assisted water splitting. Surprisingly, the unique Co0.8Ru0.2 alloy exhibits the potential to surpass the pure Ru metal in optimizing d-band centers and the adsorption of reaction intermediates. Overall, the a/c-alloy/oxide bifunctional electrode with Ruδ+-Ru0-Coδ+ multi-active sites was constructed by one-step corrosion, providing a new idea for designing efficient a/c-alloy/oxide electrodes and realizing industrial urea-assisted water splitting.

Spider silk inspired ultrafine carbon nanotubes-crosslinked porous carbon fibers for Zn-air batteries

There is a critical need for the development of low-cost, highly efficient, and stable bifunctional oxygen electrocatalysts for the advancement of Zn-air battery (ZAB). This study presents an Fe-, Ni-, and N-co-doped porous carbon material (FeNiN-CF-15) synthesized through the pyrolysis of a mixture combining the melamine and electrospun fibers. This material comprises carbon fiber substrates and spider silk-like ultrafine carbon nanotubes (CNTs) catalytically grown from FeNi alloys. With a high N doping level (12.9 at%), large specific surface area (385.18 m2 g−1), and conductive carbon network composed of CNTs, the new electrocatalyst exhibits outstanding bifunctional oxygen electrocatalytic performances. Specifically, it achieves a half-wave potential of 0.853 V for oxygen reduction reaction (ORR) and 1.571 V for oxygen evolution reaction (OER) at 10 mA cm−2. The exceptional ORR/OER electrocatalytic activity enables the FeNiN-CF-15-based liquid ZAB to deliver a high initial energy efficiency of 62.12 %, narrow charging/discharging voltage gap of 0.742 V, and robust cycling stability within 960 cycles for 320 h at 5 mA cm−2. Additionally, the reported electrocatalyst is proven competent for use in a flexible ZAB.