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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]

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]

Exploring high-activity electrocatalysts for water electrolysis is a pivotal field of hot research as hydrogen is a very promising renewable energy source and bountiful in supply. Understanding the structure–composition–property relationships is the key for engineering improved electrocatalysts. We herein report a rational design on Ru-RuO 2 hybrid nanoparticles decorating carbon nanotubes composites electrocatalysts (Ru-RuO 2 /CNT), which shows impressively high activity toward hydrogen/oxygen evolution reaction (HER/OER) in all pH aqueous electrolytes. The Ru-RuO 2 /CNT, as an OER catalyst, requires ultralow overpotentials of 0.18 V, 0.27 V and 0.21 V to drive the current density of 10 mA cm−2 in acidic, neutral and alkaline media, respectively. Meanwhile, the catalyst also exhibits superior HER activity with the current density of 10 mA cm−2 at −0.063 V, −0.048 V and −0.012 V in acidic, neutral and alkaline media, respectively. Systematic characterizations and comprehensive electrochemical studies coupling with theoretical calculations verify that Ru favorably works with RuO 2 and CNT to synergistically contribute such highly desirable electrocatalytic activity. The bifunctional catalytic properties, in conjunction with its pH-universal compatibility, inspire us to an asymmetric-electrolyte electrolyzer was set up, which can harvest the electrochemical neutralization energy with implementing electrolysis H 2 generation with a current density of 10 mA cm−2 at an applied voltage of 0.73 V. The as-developed asymmetric-electrolyte electrolyzer, by coupling high-activity but not too expensive electrocatalysts with optimizing the catalytic efficiency in their favorable electrolyte, potentially provides an environmental-friend and energy-saving avenue for the future electrolysis H 2 generation. Image 1 • Bifunctional electrocatalysts for All-pH-electrolyte HER and OER. • High catalytic activity, good durability, and low cost. • Electrochemical neutralization energy was harvested for assisting electrolysis H 2 generation. • Water electrolysis in an asymmetric-electrolyte electrolyzer was implemented within 0.73 V. [ABSTRACT FROM AUTHOR]

A reliable strategy has been developed to prepare Ni2P nanofilms on carbon nanosheets (CNS) nanohybrids (Ni2P/CNS), which involves the preparation of three-dimensional (3D) CNS followed by in situ growth of Ni2P nanofilms on the surface of CNS. The Ni2P/CNS nanohybrids possess a robust 3D hierarchical structure, in which the Ni2P films are solidly overlaid on the surface of the CNS. The Ni2P/CNS nanohybrid was characterized by a variety of techniques, including X-ray diffraction (XRD), electron microscopy, X-ray photoelectron spectroscopy (XPS), etc. A series of electrochemical tests demonstrate the Ni2P/CNS nanohybrid shows high catalytic activity and excellent stability towards the hydrogen evolution reaction (HER) in pH-universal electrolyte, that is, in acidic, neutral, and basic media. The outstanding performance for Ni2P/CNS is correlated with the synergic effects between Ni2P and CNS associated with its unique and robust structure. [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]

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]

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]

It is highly desirable to develop low-cost and highly-efficiency electrocatalysts toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) for implementing full water splitting in developing a sustainable green energy system. Herein, we report a reliable and facile anion-exchange reaction strategy for conversion of one-dimensional (1D) Co 3 O 4 nanowires (NWs) into CoP porous nanowires (PNWs). Notably, such evolution process provides the as-formed CoP PNWs with significantly improved defect sites and thus endows the CoP PNWs with a high electrochemical activity surface area. Accordingly, the CoP PNWs exhibit outstanding catalytic activity toward HER and OER when serving as bifunctional electrocatalysts, achieving a current density of 10 mA cm −2 with low overpotentials of 147 and 326 mV for HER and OER, respectively. We demonstrate the water splitting electrolyzer with such CoP PNWs electrocatalyst as cathode and anode can be driven by a double A battery and a solar panel (1.5 V). The advantages, including facile and low-cost synthetic process, high activity for HER and OER, endow the as-developed CoP PNWs to be one of the most promising candidates for full water splitting system. [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 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]

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]