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Sodium borohydride (NaBH4) has earned recognition as a promising hydrogen carrier, attributed to its exceptional hydrogen storage capacity, boasting a high theoretical storage capacity of 10.8 wt %. Nonetheless, the utilization of traditional pyrolysis and hydrolysis methods still presents a formidable challenge in achieving controlled hydrogen generation especially under ambient conditions. In this work, we report an innovative electrochemical strategy for production H2 by coupling NaBH4 electrooxidation reaction (BOR) at anode in alkaline media with hydrogen evolution reaction (HER) at cathode in acidic media. To implement this, we have developed a bifunctional electrocatalyst denoted as Pd‐Mo2C@CNTs, wherein Pd nanoparticles are grown in situ on Mo2C embedded within N‐doped carbon nanotubes. This electrocatalyst demonstrates exceptional performance in catalyzing both alkaline BOR and acidic HER. We have developed a hybrid acid/alkali cell, utilizing Pd/Mo2C@CNTs as the anode and cathode electrocatalysts. This configuration showcases remarkable capabilities for self‐sustained, precise, and uninterrupted indirect release of H2 stored in NaBH4, even at high current densities of 100 mA cm−2 with a Faraday efficiency approaching 100 %. Additionally, this electrochemical device exhibits significant promise as a fuel cell, with the ability to deliver a maximum power density of 20 mW cm−2. [ABSTRACT FROM AUTHOR]

Transition metal single atoms anchored on nitrogen‐doped carbon (M‐N‐C) matrix with M‐N‐C active sites have shown to be promising catalysts for both hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). Herein, a hybrid catalyst with low‐level loading of atomic Pt and Co species encapsulated in nitrogen‐doped graphene (Pt@CoN4‐G) is developed. The Pt@CoN4‐G shows low overpotential for HER in wide‐pH electrolyte and manifests improved mass activity with almost eight times greater than that of Pt/C at an overpotential of 50 mV. The Pt@CoN4‐G also exhibits a top‐level ORR activity (half‐wave potential, E1/2 = 0.893 V) and robust stability (>200 h) in alkaline medium. Using theoretical calculations and comprehensive characterizations , the strong metal–support interactions between Pt species and CoN4‐G support and synergistical cooperation of multiple active sites are clarified. A flow alkali‐Al/acid hybrid fuel cell using Pt@CoN4‐G as cathode catalyst delivers a large power density of 222 mW cm−2 with excellent stability to achieve simultaneously hydrogen evolution and electricity generation. In addition, Pt@CoN4‐G endows a flow Zn‐air battery with high power density (316 mW cm−2), good stability under large current density (>100 h at 100 mA cm−2), and long cycle life (over 600 h at 5 mA cm−2). [ABSTRACT FROM AUTHOR]

The development of high‐efficient electrocatalysts with low applied voltage and robust stability is of great importance for electrolysis of water. In this work, a bifunctional electrode has been developed by growing palladium‐modified FeCoS2 nanosheet arrays on Ni foam (Pd‐FeCoS2 NAs/NF), which can serve as anode and cathode for alkaline water splitting with high activities and ultra‐strong durability. The Pd‐FeCoS2 NAs/NF shows overpotentials of 130 mV for hydrogen evolution reaction (HER) and 202 mV for alkaline oxygen evolution reaction (OER) at 10 mA cm−2. The alkaline electrolyzer is built by employing Pd‐FeCoS2 NAs/NF as cathode and anode, delivering a current density of 50 mA cm−2 at 1.59 V. Moreover, the electrolyzer can run stably for 600 h with negligible decline. [ABSTRACT FROM AUTHOR]

The development of highly efficient cathodes for hydrogen production that can operate in a suitable pH condition is a daunting challenge in microbial electrolysis cells (MECs). Herein, an asymmetric neutral‐alkaline double‐chamber microbial electrolysis cells (AMECs) by using conventional carbon brush with microorganism attached as neutral anode and the Ru/CNTs electrode as alkaline cathode, respectively, was proposed. To implement this, a hybrid with ruthenium nanoparticles loaded on conductive carbon nanotubes (Ru/CNTs) was prepared by a reduction deposition method, which exhibited comparable electrocatalytic performance to the expensive benchmark Pt/C catalysts for hydrogen evolution reaction (HER). Compared to the traditional MECs running in symmetric neutral electrolyte, the as‐developed AMEC displayed a higher current density of 17.13 A m−2 and hydrogen production rate of 0.167 m3 m−2 d−1. The present AMEC provides an energy‐saving and cost‐effective process technology for electrolysis H2 generation. [ABSTRACT FROM AUTHOR]

WS2 nanosheets hold great promise for a variety of applications yet faces a grand challenge in terms of large‐scale synthesis. We report a reliable, scalable, and high‐yield (>93 %) synthetic strategy to fabricate WS2 nanosheets, which exhibit highly desirable electrocatalytic properties toward both the alkaline sulfion (S2−) oxidation reaction (SOR) and the acidic hydrogen evolution reaction (HER). The findings prompted us to develop a hybrid alkali‐acid electrochemical cell with the WS2 nanosheets as bifunctional electrode catalysts of alkaline anodic SOR and acidic cathodic HER. The proof‐of‐concept device holds promise for self‐power or low‐electricity electrolytic H2 generation and environmentally friendly recycling of sulfion with enhanced electron utilization efficiency. [ABSTRACT FROM AUTHOR]

Hydrogen (H2) has been utilized as a versatile feedstock or promising energy carrier in a variety of fields, yet the implementation of high‐rate H2 production presents a grand challenge for its readily accessible application. Herein, a newly alkali‐Al/acid hybrid fuel cell (3AHFC) that shows the capability of rapidly producing H2 upon delivering a considerably high energy density is reported, which is set up by paring Al anode in alkaline anolyte with acidic catholyte and a relatively cheap nanohybrid of Ru nanoparticle decorating crumpled reduced graphene oxide (Ru/c‐rGO) as cathode catalysts. It is demonstrated that the 3AHFC can release a power density of up to 240.6 mW cm−2 with a Faradic efficiency of approaching 99% for fast H2 generation (300 mA cm−2). Such hybrid electrolyte H2‐generation fuel cell can also be extended for either seawater anolyte or metallic Mg anode, presenting great promise for the practice feasibility of on‐site H2 production for applications in tough or even extreme environments. [ABSTRACT FROM AUTHOR]

Multi‐dimensional hierarchical nanostructures can efficiently promote the mass transportation and electron transfer of electrocatalysts, which can boost the electrocatalytic performance. In this study, we report the design of a hierarchical carbon/metal nanostructure (Co@CNFs) with the combination of 0D cobalt metal nanoparticles, 1D carbon nanofibers, and 2D carbon nanosheets as a bifunctional oxygen reduction/evolution reaction (ORR/OER) catalyst. The Co@CNF catalysts are prepared by using a facile approach of combining electrospinning, impregnation growth of ZIF‐67 nanosheets, and high‐temperature carbonization. Through rationally optimizing the synthesis conditions, including the chemical concentration and carbonization temperature, the optimal catalyst of Co@CNFs‐50‐800 features a hierarchical structure of continuous carbon nanofibers (CNFs)‐anchored carbon nanosheets wrapping Co nanoparticles, which holds decent catalytic activities in term of a half‐wave potential of 0.8 V for the ORR and a potential of 1.54 V for the OER at 10 mA cm−2. A rechargeable Zn‐air battery is set up using the catalyst as the air cathode, which exhibits a high specific capacity of 809 mAh g−1 and a peak power density of 165.5 mW cm−2, as well as a good durability up to 1000 charging‐discharging cycles (>160 h), which is even better than the benchmark Pt/C+RuO2 catalyst. This study provides a rational strategy to design hierarchically nanostructural catalysts to boost the mass transportation and electron transfer of electrocatalytic reactions. [ABSTRACT FROM AUTHOR]

Glycerol, as the major by‐product of biodiesel, can be oxidized into diverse value‐added chemical products via either traditional chemical methods or electrochemical routes. Electrocatalytic glycerol oxidation reaction (GOR) driven by renewable‐derived electricity (e.g., wind and solar) is a promising pathway for fine chemicals production. In an electrochemical cell, GOR can be coupled with various cathodic reactions, including hydrogen evolution reaction (HER), CO2 reduction reaction (CO2RR), and oxygen reduction reaction (ORR); in this manner, different benefits of either energy effectiveness or additional value‐added products can be obtained depending on the cathode reduction reaction selected. Comprehensively understanding of electrocatalytic GOR and the associated processes is of great significance to promote its industrial application. Herein, recent progress of GOR is focused on. The background of biomass‐derived glycerol valorization to energy and value‐added chemicals as well as the electrochemical conversion techniques via GOR is introduced. Then, the electrocatalytic reaction pathways, the potential application of GOR, and the measurement method for products are also discussed and summarized. Special emphasis is put on the design and the development of high‐selectivity and high‐activity electrocatalysts for GOR. Finally, the challenges and the future prospects in the fields of GOR are highlighted. [ABSTRACT FROM AUTHOR]

Development of low cost electrocatalysts with outstanding catalytic activity and stability for oxygen evolution reaction (OER) in acid is a major challenge to produce hydrogen energy from water splitting. Herein, a novel metal‐free electrocatalyst consisting of a oxygen‐functionalized electrochemically exfoliated graphene (OEEG) nanosheets array is reported. Benefitting from a vertically aligned arrays structure and introducing oxygen functional groups, the metal‐free OEEG nanosheets array exhibits superior electrocatalytic activity and stability toward OER with a low overpotential of 334 mV at 10 mA cm−2 in acidic electrolyte. Such a high OER performance is thus far the best among all previously reported metal‐free carbon‐based materials, and even superior to commercial Ir/C catalysts (420 mV at 10 mA cm−2) in acid. Characterization results and electrochemical measurements identify the COOH species in the OEEG acting as active sites for acidic OER, which is further supported by atomic‐scale scanning transmission electron microscopy imaging and electron energy‐loss spectroscopy. Density functional theory calculations reveal that the reaction pathway of dual sites that is mixed by zigzag and armchair edges (COOH‐zig‐corner) is better than the pathway of single site. [ABSTRACT FROM AUTHOR]

It is highly attractive to develop efficient water electrolysis route to implement hydrogen generation in a low‐cost way, which while requires excess energy to surmount the activation barriers majorly limited by oxygen evolution reaction at anode side. Herein, we report an acid‐alkali asymmetric‐electrolyte electrolyzer (AAAE) that can achieve substantial energy saving for electrolysis hydrogen generation, thanks to the assistance of electrochemical neutralization energy (ENE) and urea oxidation reaction (UOR). To this end, free‐standing Ni(OH)2 nanosheets on carbon cloth (Ni(OH)2−NSs/CC) is fabricated as catalytic anode for alkaline UOR, which manifests impressively high catalytic activity with delivering 10 mA cm−2 at 1.32 V and long‐term durability. The as‐developed AAAE only requires an applied voltage of 0.66 V to release the electrolysis current of 10 mA cm−2, yielding the H2 Faraday efficiency close to 100 % along with H2 production rate of 183.8 μmol h−1. [ABSTRACT FROM AUTHOR]

The development of high-kinetic catalysts for the hydrogen evolution reaction (HER) in a neutral electrolyte is of great importance but unfortunately remains a challenge so far. Herein, we report hybrids with abundant Ru–S–Sb bonds and engineered ultrathin antimonene (Ru–S–Sb/antimonene) as highly kinetic, active, stable electrocatalysts for the HER in an aqueous neutral electrolyte. Experiments and density functional theory (DFT) calculations reveal that Ru–S–Sb bonds coupling with antimonene synergistically work to promote HER activity. The present study brings us one step closer to understand the structure–composition–property relationships and practical electrolytic H2 production. [ABSTRACT FROM AUTHOR]

We report the fabrication of self-supported Cu/Cu2O–CuO/rGO nanowire arrays on commercial porous copper foam, which exhibit excellent activity and durability for electrochemical hydrogen evolution, presenting a small onset potential of 84 mV and a low overpotential of 105 mV at a current density of 10 mA cm−2. [ABSTRACT FROM AUTHOR]

An unprecedented asymmetric-electrolyte electrolyzer is proposed using an acidic cathode for the hydrogen evolution reaction (HER) and an alkaline anode for the urea oxidation reaction (UOR), which significantly decreases the electrical energy required for electrolytic hydrogen production. [ABSTRACT FROM AUTHOR]

The development of high-activity electrocatalysts for water splitting that comprise only inexpensive, earth-abundant elements is critical but remains a daunting challenge. In this work, yolk-shell Ni3Fe/Ni3FeN was prepared by a spray-pyrolysis technique, which could be scaleable. The yolk-shell Ni3Fe/Ni3FeN presents excellent catalytic activity for the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) with overpotentials of 268 and 166 mV at 10 mA cm−2, respectively, and bears a prominent electrochemical durability. Overall water splitting with an electrolyzer containing the yolk-shell Ni3Fe/Ni3FeN as the cathode and anode only requires a cell voltage of 1.62 V to reach a current density of 10 mA cm−2. The present research not only introduces a new route for the synthesis of advanced functional electrocatalysts for overall water splitting but also sheds light on their potential commercial applications. [ABSTRACT FROM AUTHOR]

Optimized electrocatalyst that hybrids with carbon coating FeCoP x nanoparticles possesses catalytic activity toward ORR, OER and HER. Furthermore, through the design of alkali-acid electrolyzer and device integration, for the very first time, a single Zinc-air battery enable to drive an alkali-acid electrolyzer for producing hydrogen and oxygen. [Display omitted] • A one-pot scalable pyrolysis strategy to fabricate a tri-functional electrocatalyst. • High catalytic activity toward ORR&OER in alkaline and HER in acidic media. • The Zn-air battery can run stably for 1500 cycles. • An alkali-acid electrolyzer only requires 0.99 V to release an electrolysis current density of 10 mA cm−2. • A single self-made Zinc-air battery can drive an alkali-acid electrolyzer to produce hydrogen. Developing handy synthesis routes to fabricate low-cost, high-activity, and multifunctional electrocatalysts for a variety of electrochemical reactions is highly desirable so as to achieve the goal that one catalyst can be used for integrated electrolysis devices, thus greatly simplifying the electrocatalyst system processing. Here, we report a one-pot scalable pyrolysis strategy to fabricate a tri-functional electrocatalyst, i.e. , hybrids with carbon coating FeCoP x nanoparticles, which shows favorable electrocatalytic properties toward oxygen reduction reaction, oxygen evolution reaction in alkaline solution, and hydrogen evolution reaction in acidic condition. The new synthesis routes enable us to readily develop an integrated device with a Zn-air battery driving an alkali-acid electrolyzer by just using one catalyst. The present work may shed light on the practical viability of the development of multifunctional electrocatalysts for integrated devices applications. [ABSTRACT FROM AUTHOR]

[Display omitted] Designing heterostructure photocatalysts is a promising approach for developing highly efficient photocatalysts for hydrogen energy production. In this work, we synthesized a series of a covalent organic framework (COF)/g-C 3 N 4 (CN) heterojunction photocatalysts, denoted as x % COF/CN (in which x indicates the weight % of COF and x = 5, 10, 20, 30, 40, 50, 90, 95, 100), for hydrogen production. The COF, which is a key component of the photocatalyst, was prepared by assembling benzothiadiazole (BT) and pyrene (Py) derivatives as building blocks. Integrating COF rods into the two-dimensional (2D) layered g-C 3 N 4 structure significantly improved photocatalytic H 2 production. The hybrid system (30 % COF/CN) displayed an outstanding hydrogen evolution rate (HER) of 27540 ± 805 μmol g−1h−1, outperforming most known COFs and g-C 3 N 4 -based photocatalysts, besides exhibiting stable photocatalytic performance. Moreover, the apparent quantum yield (AQY) was 15.5 ± 0.8 % at 420 nm. Experimental techniques and density functional theory (DFT) calculations demonstrated that the 30 % COF/CN heterostructure has broad visible-light absorption, adequate band energy levels, and the best chemical reactivity descriptors compared to the individual components, resulting in effective carrier separation and excellent performance. Our findings offer a valuable strategy for developing highly efficient and stable heterojunction photocatalysts for visible-light‐driven H 2 evolution. [ABSTRACT FROM AUTHOR]

A facile self-templated carbonization strategy is developed for fabrication of a bifunctional electrocatalyst with uniform distribution of F, N heteroatoms, mesoporous channels and abundant edge-defect by direct pyrolysis of F, N -containing covalent organic framework (F-COF) precursor. The designed catalyst exhibits excellent bifunctional catalytic activity with a small OER-ORR potential gap of 0.79 V. The assembled ZAB delivers a high peak density of 206.3 mW cm−2 and good cyclic stability. [Display omitted] • F, N co-doped porous carbon (F-NPC) was facile prepared by in situ pyrolysis of fluoric COF precursor. • Experiments combined with theoretical calculation confirmed the significant contribution of F in boosting the catalytic reactivity. • The designed F-NPC catalyst shows superior ORR and OER activity. • The assembled ZAB using F-NPC catalyst displays high peak power density and excellent durability. The construction of heteroatom-doped metal-free carbon catalysts with bifunctional catalytic activity for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is highly desired for Zn-air batteries, but remains a great challenge owing to the sluggish kinetics of OER and ORR. Herein, a self-sacrificing template engineering strategy was employed to fabricate fluorine (F), nitrogen (N) co-doped porous carbon (F-NPC) catalyst by direct pyrolysis of F, N containing covalent organic framework (F-COF). The predesigned F and N elements were integrated into the skeletons of COF precursor, thus achieving uniformly distributed heteroatom active sites. The introduction of F is beneficial for the formation of edge-defects, contributing to the enhancement of the electrocatalytic activity. Attributing to the porous feature, abundant defect sites induced by F doping, as well as the strong synergistic effect between N and F atoms to afford a high intrinsic catalytic activity, the resulting F-NPC catalyst exhibits excellent bifunctional catalytic activities for both ORR and OER in alkaline mediums. Furthermore, the assembled Zn-air battery with F-NPC catalyst shows a high peak power density of 206.3 mW cm−2 and great stability, surpassing the commercial Pt/C + RuO 2 catalysts. [ABSTRACT FROM AUTHOR]

• A novel Mo 2 C loaded nitrogen-doped porous carbon (Mo 2 C/NC-800) is synthesized. • The Mo 2 C/NC-800 catalyst delivers impressively high activity and durability in all-pH electrolytes. • The hybrid neutral-alkaline MEC using Mo 2 C/NC-800 as the cathode catalyst can achieve current density of 20.0 mA m−2 at H 2 generation rate of 170.5 L m−2 d−1 only by applying voltage of 1.0 V. Microbial electrolysis cells (MECs) show promise in energy-effective hydrogen (H 2) production by harvesting electric energy from wastewater, while the implementation of such a desirable technique faces challenges of expensive cathodic catalysts and unfavorable neutral electrolyte for hydrogen evolution reaction (HER). This work presents a simple and cost-effective pyrolysis route to fabricate hybrid electrocatalysts of Mo 2 C loaded nitrogen-doped porous carbon (Mo 2 C/NC). The Mo 2 C/NC-800 catalyst delivers impressively high activity and durability in pH-varied electrolyte from alkali, neutral and acid, particularly in alkali condition (e.g. 1.0 M KOH) where the overpotential@10 mA cm−2 is only 138 mV which is comparable to the commercial Pt/C catalysts. A hybrid neutral-alkaline MEC is therefore developed that uses Mo 2 C/NC as the cathode catalyst for H 2 production. The system requires an applied voltage of 1.0 V to achieve current density of ∼20.0 A m−2 at H 2 generation rate of 170.5 L m−2 d−1. This MEC performance is considerably higher than that of the traditional symmetric neutral counterpart that requires an applied voltage of 1.0 V to achieve current density of ∼18.0 A m−2 at H 2 generation rate of 159.4 L m−2 d−1 indicating promising potential of Mo 2 C/NC electrocatalyst to be applied in MEC device for H 2 generation. Novel Mo 2 C loaded nitrogen-doped porous carbon (Mo 2 C/NC-800) is successfully synthesized. The Mo 2 C/NC-800 catalyst delivers impressively high activity and durability in all-pH electrolytes, particularly in alkali condition (e.g. 1.0 M KOH) where the overpotential@10 mA cm−2 is only 138 mV which is comparable to the commercial Pt/C catalysts. The hybrid neutral-alkaline MEC using Mo 2 C/NC-800 as the cathode catalyst can achieve current density of 20.0 mA m−2 at H 2 generation rate of 170.5 L m−2 d−1 only by applying voltage of 1.0 V. [Display omitted] [ABSTRACT FROM AUTHOR]

Exploring low-cost, highly efficient, and sustainable non-precious electrocatalysts for electrolytic H 2 generation is driving research for the sustainable green urban development. Herein, we present a simple synthetic approach, through a two-step process, to prepare the bifunctional electrode of Co 3 O 4 –C@FeMoP hybrid micro rods/nanosheets anchored on nickel foam (NF), in which the Co 3 O 4 –C microrods grown on NF surface are decorated by FeMoP nanosheet layers, which is directly grown through a simple hydrothermal followed by post-phosphorization processes. The obtained hybrid hierarchical Co 3 O 4 –C@FeMoP/NF shows a significant enhancement in the electrocatalytic activities of oxygen/hydrogen evolution reactions (OER/HER) in comparison to the individual Co 3 O 4 –C and FeMoP nanostructures, thanks to more heterointerface active sites provided by FeMoP nanostructures with three-dimensional (3-D) layered architectures. The Co 3 O 4 –C@FeMoP/NF catalyst exhibits a relatively small overpotential of 200 mV vs. RHE for OER to achieve 20 mA/cm2 and 123 mV vs RHE at 10 mA/cm2 for HER along with excellent durability in alkaline electrolytes. We demonstrate the bifunctional electrocatalytic electrode as the electrolyzer for the generation of H 2 via water splitting at small applied voltage of 1.61 V to achieve 10 mA/cm2 and good stability for 24-h continuous running. • Synthesis of high-activity catalyst material Co 3 O 4 –C@FeMoP/NF. • Decent electrocatalytic activity toward OER and HER in alkali. • Alkaline water electrolysis system with bifunctional electrocatalyst electrode. [ABSTRACT FROM AUTHOR]

Hydrogen, as the one of clean energy source, has the advantages of high energy density and carbon-free emission. Water electrolysis is one of the most promising ways to generate hydrogen, but the rather high energy required seriously hinders its widespread applications yet. In this study, we report an alkaline electrolyzer to implement energy-saving H 2 generation by coupling cathodic hydrogen evolution reaction (HER) with anodic glucose oxidation reaction (GOR) other than oxygen evolution reaction, in which nickel-doped MoS 2 nanoparticles (Ni–MoS 2 NPs) has been developed as bifunctional electrocatalyst for HER and GOR. The electrolyzer only requires a cell voltage of 1.67 V to reach an electrolysis current density of 10 mA cm−2, about 270 mV lower than the corresponding value in the traditional electrolyzer. Electrolytic H 2 generation with the assistance of biomass derived materials may open a new way for the future sustainable development. • Ni-doped MoS 2 was fabricated as bifunctional electrocatalyst. • Biomass derived glucose as the electron donor to replace water. • Glucose assisted electrolytic H 2 generation can reduce energy consumption. [ABSTRACT FROM AUTHOR]

• Bifunctional electrocatalyst of Pd decorating P, N-codoped carbon nanostructures. • A hybrid acid/alkali cell for energy-saving and self-powered generation of H 2. • Indirect releasing H 2 stored in hydrazine by an electrochemical strategy. • Efficient, controllable and continuous release high-purity H 2 from H 2 carrier. Liquid-phase hydrogen (H 2) carriers have received widespread attention owing to their convenient and safe storage and transportation of H 2. Among the various liquid-phase H 2 carriers, hydrazine (N 2 H 4) shows promising applications due to its ability to release H 2 in aqueous solutions via the dehydrogenation process with the assistance of suitable catalysts, which yet produces N 2 /H 2 mixture gas and thus require additional high-energy purification process. In this work, we propose a self-powered electrochemical strategy to indirectly release high-purity H 2 stored in N 2 H 4 by developing a hybrid acid/alkali electrochemical cell, which is set up by coupling alkaline anode for N 2 H 4 electrooxidation reaction (HzOR) with acidic cathode for hydrogen evolution reaction (HER), respectively. For this purpose, Pd nanoparticles uniformly decorating P, N-codoped hollow dodecahedron carbon nanostructures (Pd/PNC) is prepared as bifunctional electrocatalyst for both HzOR and HER, which exhibits high electrocatalytic activity and robust stability. Density functional theory (DFT) calculations imply that P, N-codoping substrate of Pd is conductive to optimize adsorption/desorption sites upon electrocatalysis of HzOR and HER by lowing Gibbs free energy and improving activity. The as-assembled hybrid acid/alkali cell is capable of delivering a maximum power density of 18.2 mW cm−2 and can run stably for 120 h, implementing H 2 generation in a voltage or power controllable manner. This work may inspire exploring the way for efficient, energy-saving, and continuous generation of high-purity H 2. [ABSTRACT FROM AUTHOR]

It is vital to develop a high activity, stability and inexpensive hydrogen evolution reaction (HER) catalyst for electrochemical hydrogen evolution. A high-temperature reaction approach that is Co nanocrystals on carbon support (XC-72R) and selenylation to synthetize CoSe 2 /C nanocrystals is used, and the effect of temperature on CoSe 2 /C nanocrystals is studied. The morphology and catalytic properties of CoSe 2 /C nanocrystals annealed at different temperatures are compared in 0.5 M H 2 SO 4. The results indicated the coralline-like CoSe 2 /C-650 nanocrystals have a high performance for HER with Tafel slopes of 45.73 mV·dec−1 and onset potential of −196 mV vs. RHE. The stability maintained for at least 40 h and the Faraday Efficiency (FE) of H 2 is nearly 98%. The outstanding HER performance of CoSe 2 /C-650 is due to its characteristic cora-like frame CoSe 2 nanocrystals embedded into supernal conductive XC-72R, which not only offer affluent active reaction sites, but also boost the capacity of charge transportation in HER process. A reliable strategy is developed to fabricate coralline-like CoSe 2 nanocrystals on carbon support (XC-72R); the effect of temperature on controlling CoSe 2 nanocrystals is studied. The coral-like CoSe 2 /C-650 shows high catalytic activity and stability, superior to that the obtained CoSe 2 at other temperature, the onset potential for HER of −196 mV vs. RHE and Tafel slopes of 45.73 mV·dec−1. The electrode also has excellent durability, catalytic activity being maintained for over 40 h and the FE was calculated of H 2 is nearly 98%. The unique cora-like architecture constructed by CoSe 2 nanocrystals embedded into highly conductive XC-72R, which can not only offer rich active reaction sites, but also boost the ability of charge transportation in HER process. Image 1 • A CoSe 2 nanocrystals embedded into carbon support show a coralline-like structure. • The effect of temperature on controlling CoSe 2 nanocrystals. • The CoSe 2 /C-650 with a Tafel slopes of 45.73 mV•dec−1. [ABSTRACT FROM AUTHOR]

• The CoP|S has coral-like nanoporous structures and allows the release of gas evolution in nano-scale design. • Stable nanoporous CoP|S with abundant active sites are fabricated through a simple annealing method. • S-substituting can control the electronic structure and favor more suitable H adsorption of CoP|S to promote HER activity. • Nanoporous CoP|S electrodes present the improved HER performance compared with CoP. The morphology and crystallographic surface can influence the catalytic HER activity of electrocatalyst. With sufficient active sites and surface area, nanoporous materials with three-dimensional interconnected porous networks have shown the promising application in electrocatalyst. In this work, we report a simple method that can synthesize the self-supported nanoporous cobalt phosphosulfate (CoP|S) electrocatalyst. Theoretical calculation shows that the phosphorus substitution by sulfur can control the electronic structures of the active sites and accelerate charge transfer of CoP, therefore improving HER activity. The experimental study shows that nanoporous CoP|S electrodes present the improved HER performance compared with CoP in alkaline media and acidic media, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • A hypotoxic molten-salt-assisted method was developed to synthesize Co 2 P (t-Co 2 P). • The t-Co 2 P can spontaneously transform into CoOOH in alkaline solutions. • The t-Co 2 P can effectively electrocatalysis acidic hydrogen evolution reaction. • CoOOH can effectively electrocatalysis alkaline sulfite (SO 3 2–) oxidation. • A hybrid acid-alkali electrolyzer was built for H 2 generation and sulfite removal. Co 2 P has been widely applied in a variety of applications yet still faces challenges in implementing hypotoxic and large-scale synthesis. We here report a scalable synthetic route to produce tussock-like nanostructured Co 2 P (t-Nano Co 2 P), which exhibits high-performance electrocatalytic properties toward acidic hydrogen evolution reaction (HER). Such t-Nano Co 2 P can evolve to CoOOH nanoplates that show excellent electrocatalytic activity for sulfite oxidation reaction (SOR) in alkaline solution. The findings encourage us to construct a hybrid acid/alkali electrolyzer with t-Nano Co 2 P and its CoOOH derivative as catalysts of acidic cathode for HER and alkaline anode for SOR, respectively, which performs excellently with capability of synchronous generation of H 2 and sulfate in an industrial-level rate at a relatively low applied voltage. The proof-of-concept electrolyzer, by virtue of the viability of scalable synthesis and high-production yield, holds great promise for co-production of H 2 and sulfate in an energy-effective and environmentally-friendly manner. [ABSTRACT FROM AUTHOR]

Exploring efficient and low-cost oxygen evolution reaction (OER) electrocatalysts is of crucial importance. Here, we report a surface plasmon resonance (SPR) engineering strategy to regulate surface reconstruction of CoFeB nanosheets by decorating plasmonic MoO 2 nanospheres (MoO 2 /CoFeB), in which the SPR effect of MoO 2 offers an additional acceleration for the conversion of inactive Co species to active cobalt oxyhydroxide on the CoFeB surface under visible light. Our results also indicate the real reactive surface for CoFeB is in the form of CoFeOOH with adsorbed BO 2 − that has positive effect. The MoO 2 /CoFeB shows superior OER performance with a low overpotential (209 mV at J =10 mA cm−2). However, such an accelerated reconstruction behavior would be self-terminated once the anodic voltage increases to thoroughly oxidize the MoO 2 to high valence state (+6). This work inspires us to develop a rational strategy to improve the catalytic performance by properly regulating the surface reconstruction. [Display omitted] • SPR effect of MoO 2 was applied for regulating surface reconstruction of CoFeB to enhance the electrocatalytic OER process. • The MoO 2 /CoFeB nanohybrid electrocatalyst shows attractive OER performance with a low overpotential of 209 mV at 10 mA cm–2. • An insightful fundamental understanding of the reaction interface for metal borides was presented. [ABSTRACT FROM AUTHOR]

The rational design of cost-effective and high-activity electrocatalyst for hydrogen evolution reaction (HER) is a crucial field of research for achieving the best way to promote “green energy”. Here, we develop a simple route to prepare nanohybrids of three-dimensional graphene loading MoO 2 Mo 2 C nanoparticles (MoO 2 Mo 2 C/G), which were characterized using X-ray diffractometer (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), demonstrating the MoO 2 Mo 2 C/G has unique features with high conductivity, robust structure, and high surface area. The as-developed MoO 2 Mo 2 C/G nanohybrid shows great potential to replace Pt-based electrocatalyst for hydrogen evolution reaction (HER) due to its cheapness, high catalytic activity and considerable stability. [ABSTRACT FROM AUTHOR]

• A facile dual-sites method is developed to modify MoO 2 nanospheres. • The optimal Ni and Fe co-doped MoO 2 shows low overpotential and good stability. • The synergistic catalytic mechanism for OER is illustrated. Oxygen evolution reaction (OER) is of critical importance in the area of electrocatalysis as it is frequently involved in a diversity of electrochemical devices. Molybdenum-based materials, thanks to their metallic character induced high conductivity, have been widely studied as catalysts for a variety of reactions but few reports for oxygen evolution reaction (OER). Herein, we report a dual-sites modifying strategy to modulate electrocatalytic properties of metallic MoO 2 nanospheres toward OER, which is implemented by a one-pot synthesis process to prepare nickel and iron co-doped molybdenum oxide (Mo 0.9 Ni 0.05 Fe 0.05 O 2). The introduction of dual sites (i.e. , Ni and Fe) on MoO 2 nanospheres surface can tune the surface electronic structure and local-chemical environment with generation of high-valence Mo and hydroxyl-rich surface, synergistically contributing to the improved electrocatalytic performance in terms of stability and activity. Density functional theory (DFT) calculation indicates Fe-doping site favors for enhancing the turnover efficiency (TOF) while the Ni-doping site facilitates the first proton coupled electron transfer (PCET) upon electrocatalysis of OER. The Mo 0.9 Ni 0.05 Fe 0.05 O 2 requires only 249 mV of overpotential to reach a current density of 10 mA cm−2 with excellent stability for 80 h. This study expands the research on molybdenum-based OER catalysts and gains insight into the origin of both the activity and stability of Ni/Fe-doping reactive sites. [ABSTRACT FROM AUTHOR]

• RuCo@NG/N-GNs catalyst were fabricated via one-step annealing strategy. • RuCo@NG/N-GNs holds unique structure and plenty of active sites. • RuCo@NG/N-GNs exhibits a top-level acidic OER and alkaline HER performance. • DFT calculations reveals the critical role of Co in enhancing HER and OER. There remain certain critical issues for hydrogen production in both proton exchange membrane (PEM) and alkaline water electrolysis, the former of which faces daunting challenges in the development of high-activity and high-stability catalysts for acidic oxygen evolution reaction (OER), while the latter one strongly demands enhancing the sluggish kinetic of alkaline cathodic hydrogen evolution reaction (HER). Herein, we reported a facile one-step annealing strategy for fabricating hybrid electrocatalyst with RuCo alloy nanoparticles encapsulated by N-doped graphite loading on N-doped graphite nanosheets (RuCo@NG/N-GNs), which manifests highly desirable electrocatalytic features toward both acidic OER and alkaline HER with impressively high activity, fast kinetic and excellent stability. The optimized RuCo@NG/N-GNs requires a quite low overpotential of 209 mV at 10 mA cm−2 for acidic OER with a quite low Tafel slope of 56 mV dec−1, and demands a striking low overpotentials of 9 mV at 10 mA cm−2 toward alkaline HER with a Tafel slope of as low as 30 mV dec−1. Experiments combined with density functional theory (DFT) calculations reveal that the critical role of Co element in enhancing the HER and OER performance. For HER, the surface Co improves the oxophilicity of catalyst that indirectly aids the proton donation in alkaline; and for OER, surface Co itself acts as active sites to directly aid the reaction. The relatively low-cost electrocatalyst in this work is expected to inspire more innovative researches to step forward the large-scale commercial practice feasibility of PEM and alkaline water splitting. [ABSTRACT FROM AUTHOR]

A bifunctional electrode with 1D nickel–iron phosphide and molybdenum dioxide (NFPMO) grown on nickel foam presents highly outstanding electrocatalytic performance for overall water splitting. • Electrode of NiFeP-MoO 2 hybrid nanorods on Ni foam for water electrolysis. • High-activity and high-stability electrocatalyst towards HER and OER. • The voltage for water splitting at j = 10, 100 mA cm−2 is only 1.41 V and 1.65 V. The research about inexpensive and efficient electrocatalyst plays a significant role in electrocatalyzing H 2 production from water splitting. We herein report a novel hybrid 1D heterogeneous nanorods based on nickel–iron phosphide and molybdenum dioxide (NFPMO) grown on nickel foam that presents highly outstanding electrocatalytic performance in electrochemical overall water splitting, both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The applied cell voltage of employing NFPMO electrode in overall water splitting merely require 1.41 V and 1.65 V at 10 mA cm−2 and 100 mA cm−2 working electrolysis current density, respectively, and it can bear high stably upon hundreds of hours long-term electrolysis operation. The synergistic effects of heterogeneous structure in 1D nanorods obviously accelerate the electrocatalytic activity, as demonstrated by not only electrochemical tests but also coupling systematic electrochemical study with density functional theory (DFT) calculation. [ABSTRACT FROM AUTHOR]

• A sophisticated Ru/3DNCN catalyst were prepared through the template-assisted method. • Ru/3DNCN holds unique 3D porous interconnected structure and plenty of active sites. • Ru/3DNCN exhibits a top-level HER activity and robust stability in a wide pH range. • A Zn-H 2 fuel cell was assembled for hydrogen evolution and electricity generation. The rational design of a highly active, stable and Pt-free electrocatalyst for hydrogen evolution reaction (HER) is critical to the development of renewable energy conversion systems but extremely challenging. Herein, a facile top-down strategy is presented to synthesize ultrafine Ru nanoparticles confined in three-dimensional (3D) porous nitrogen-doped carbon nanosheets (Ru/3DNCN). Compared with the state-of-the-art Pt/C catalyst, the Ru/3DNCN exhibits significantly boosted HER activity and stability over a wide pH range, which only requires the overpotential as low as 37 mV, 66 mV, and 17 mV to achieve a current density of 10 mA cm−2 in 0.5 M H 2 SO 4 , 1.0 M PBS, and 1.0 M KOH, respectively. Moreover, an alkali-acid Zn-H 2 battery is assembled by using the Ru/3DNCN as acid cathode and Zn plate as alkaline anode. Such hybrid battery can fulfill simultaneously hydrogen evolution and electricity generation, thanks to harvesting energy from both neutralization and Zn oxidation. [ABSTRACT FROM AUTHOR]

• A tri-profitable electrochemical cell for energy saving, hydrogen production, gluconate production. • Bifunctional high-activity electrocatalyst of Fe 0.1 -CoSe 2. • Acidic hydrogen evolution and alkaline glucose oxidation. • Electrochemical neutralization energy assisted aqueous electrochemical system. Electrolytic synthesis shows great promise to address the pressing environmental and energy issues by synergy with the ever increasing renewable energy. In this article, we report a tri-profitable alkaline-acidic asymmetric electrolytic cell (3A-EC) by coupling glucose oxidation reaction (GOR) in alkaline anode with hydrogen evolution reaction (HER) in acidic cathode. We design and fabricate bifunctional electrode with iron doped cobalt diselenide nanowires on conductive carbon cloth (Fe 0.1 -CoSe 2 /CC), which shows highly attractive electrocatalytic activity and stability for GOR in alkali and HER in acid, respectively. The as-built 3A-EC only requires an applied voltage of 0.72 V to achieve an electrolytic current density of 10 mA cm−2 for H 2 and gluconate generation, thanks to successfully harvesting electrochemical energy from both glucose oxidation and neutralization. The present work presents an innovative strategy of killing three birds with one stone for saving energy and generating two value-added products. [ABSTRACT FROM AUTHOR]

One type of Pt-like electrocatalysts consisting of N,P-codoped porous carbon-encapsulated ultrafine RuP 2 nanoparticles has been developed for pH-universal hydrogen evolution reaction. • A facile and general synthetic method was developed for the fabrication of robust ruthenium diphosphide nanoparticles. • Imidazolium-based ionic polymer inhibits the aggregation of ruthenium diphosphide during phosphorization. • The bifunctional catalyst showsplatinum-like activity in pH-universal hydrogen evolution reaction. Development of cost-effective and durable electrocatalysts with Pt-like activity for pH-universal hydrogen evolution reaction (HER) is highly desirable but challenging. Herein, we report a new methodology for facile fabrication of robust electrocatalysts consisting of N, P-codoped carbon (NPC)-encapsulated RuP 2 nanoparticles around carbon nanotubes (CNTs), which shows unprecedented HER activity and high durability in all-pH range. The method involves the conformal coating of the imidazolium-based ionic polymer (ImIP) on CNTs surface, anion metathesis and subsequent phosphorization, the multistep synthetic protocol allows for deliberate modulation of the electrocatalysts. ImIP effectively inhibits the aggregation of RuP 2 during phosphorization to form small-sized RuP 2 nanoparticles, while NPC significantly increases the conductivity, intrinsic activity and stability of RuP 2. The remarkably low overpotentials of 12, 15 and 13 mV are required to achieve a current density of 10 mA cm−2 in 1.0 M KOH, 1.0 M PBS and 0.5 M H 2 SO 4 , respectively. This work provides a feasible method to develop new type of Pt-like electrocatalysts for HER in all-pH range. [ABSTRACT FROM AUTHOR]

A bifunctional electrocatalyst has been developed through integrating nickel–iron (oxy)hydroxide nanoparticles (NiFeO x (OH) y) and MoS 2 nanosheets on reduced graphene oxide. It has been deduced that MoS 2 is oxidized during oxygen evolution reaction, and the oxidized Mo species modulate the electronic structure of NiFeO x (OH) y , while NiFeO x (OH) y serves as water dissociation promoters to facilitate hydrogen evolution reaction, resulting in high electrochemical activity and durability for overall water splitting in alkaline electrolyte. • The composites consisting of NiFeO x (OH) y and vertically-oriented MoS 2 nanosheets on reduced graphene oxide has been prepared. • The promoting roles of MoS 2 nanosheets on oxygen evolution reaction have been proposed. • The integrated electrocatalyst shows high activity and superior durability for water splitting. Developing cost-effective methodologies for fabricating efficient bifunctional electrocatalysts is pivotal to boost electrochemical water splitting. Herein, we report an integrated composite, which is composed of NiFeO x (OH) y nanoparticles and vertically-oriented MoS 2 nanosheets on reduced graphene oxide (rGO) matrix (NiFeO x (OH) y @MoS 2 /rGO), for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). It has been deduced that MoS 2 is oxidized during OER, and the oxidized Mo species modulate the electronic structure of NiFeO x (OH) y to facilitate chemisorption of the oxygen species in OER. Meanwhile, NiFeO x (OH) y speeds up sluggish water dissociation in HER, and thus significantly improving HER activity of MoS 2 in alkaline electrolyte. The integrated composite shows high electrocatalytic activity and superior durability for HER and OER with low overpotentials of 170 mV at 10 mA cm−2 and 250 mV at 20 mA cm−2, respectively. This work provides new approaches to develop electrocatalysts for overall water splitting and other applications. [ABSTRACT FROM AUTHOR]

It is crucially important and highly desirable, albeit remaining a grand challenge, to develop Pt-alternative electrocatalyst toward hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) that are indispensable for a variety of electrochemical energy initiatives. We herein reported a simple synthesis recipe to prepare nanohybrids of RuS 2 quantum dots with abundant sulfur vacancies (Vs-RuS 2 QDs) supported on reduced graphene oxide (Vs-RuS 2 QDs/rGO), which exhibits impressively high electrocatalytic activity and durability toward HER in acidic medium and HOR in alkaline electrolyte, respectively, as evidenced by outperforming the state-of-the-art Pt/C catalysts with significantly promoting the catalytic kinetics. Comprehensive studies, by coupling systematic electrochemical investigation with density functional theory (DFT) calculation, signify that the synergistic effects of S vacancies, quantum size and robust 2D dimensional structure contribute to an optimized electronic structure for hydrogen bonding, leading to highly attractive catalytic performance as hydrogen electrocatalysts. We demonstrate the Vs-RuS 2 QDs/rGO hybrids perform superior performance to the commercial Pt/C as the bifunctional electrode in a proof-of-concept electrochemical device that can electrochemically harvest neutralization energy upon managing waste acid and alkali. • The Vs-RuS 2 QDs/rGO electrocatalysts show highly impressive catalytic performance. • S-vacancies provide a favorable environment for optimizing the H binding energy. • Vs-RuS 2 QDs/rGO promote kinetic toward HOR even in the high pH-value electrolyte. • Vs-RuS 2 QDs/rGO ENE battery delivers higher power density than Pt/C ENE battery. • The strategy may open a new direction to modulate the electrocatalytic activity. [ABSTRACT FROM AUTHOR]