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Electrochemical nitrogen reduction reaction (NRR) is a sustainable alternative to the Haber‒Bosch process for ammonia (NH3) production. However, the significant uphill energy in the multistep NRR pathway is a bottleneck for favorable serial reactions. To overcome this challenge, we designed a vanadium oxide/nitride (V2O3/VN) hybrid electrocatalyst in which V2O3 and VN coexist coherently at the heterogeneous interface. Since single‐phase V2O3 and VN exhibit different surface catalytic kinetics for NRR, the V2O3/VN hybrid electrocatalyst can provide alternating reaction pathways, selecting a lower energy pathway for each material in the serial NRR pathway. As a result, the ammonia yield of the V2O3/VN hybrid electrocatalyst was 219.6 µg h−1 cm−2, and the Faradaic efficiency was 18.9%, which is much higher than that of single‐phase VN, V2O3, and VNxOy solid solution catalysts without heterointerfaces. Density functional theory calculations confirmed that the composition of these hybrid electrocatalysts allows NRR to proceed from a multistep reduction reaction to a low‐energy reaction pathway through the migration and adsorption of intermediate species. Therefore, the design of metal oxide/nitride hybrids with coherent heterointerfaces provides a novel strategy for synthesizing highly efficient electrochemical catalysts that induce steps favorable for the efficient low‐energy progression of NRR. [ABSTRACT FROM AUTHOR]

Abstract Electrochemical nitrogen reduction reaction (NRR) is a sustainable alternative to the Haber‒Bosch process for ammonia (NH3) production. However, the significant uphill energy in the multistep NRR pathway is a bottleneck for favorable serial reactions. To overcome this challenge, we designed a vanadium oxide/nitride (V2O3/VN) hybrid electrocatalyst in which V2O3 and VN coexist coherently at the heterogeneous interface. Since single‐phase V2O3 and VN exhibit different surface catalytic kinetics for NRR, the V2O3/VN hybrid electrocatalyst can provide alternating reaction pathways, selecting a lower energy pathway for each material in the serial NRR pathway. As a result, the ammonia yield of the V2O3/VN hybrid electrocatalyst was 219.6 µg h−1 cm−2, and the Faradaic efficiency was 18.9%, which is much higher than that of single‐phase VN, V2O3, and VNxOy solid solution catalysts without heterointerfaces. Density functional theory calculations confirmed that the composition of these hybrid electrocatalysts allows NRR to proceed from a multistep reduction reaction to a low‐energy reaction pathway through the migration and adsorption of intermediate species. Therefore, the design of metal oxide/nitride hybrids with coherent heterointerfaces provides a novel strategy for synthesizing highly efficient electrochemical catalysts that induce steps favorable for the efficient low‐energy progression of NRR.

The engineering of robust electrocatalysts for the ethanol oxidation reaction (EOR) with cost-natural, superior electrocatalytic activity, and stability, is crucial for the scaled-up applications of direct ethanol fuel cells. Herein, a facile bottom-up hydrothermal strategy has been implemented to synthesize N,P,S triple-doped 3-dimensional (3D) graphene architectures (N,P,S-3DG) with interconnected, hierarchical porous structure, followed by Pd nanoparticles were uniformly decorated onto the N,P,S-3DG via solvothermal approach. As fabricated hybrid nanocatalyst, labeled as Pd@N,P,S-3DG, is of charming physicochemical characteristics including large electrochemically active specific surface area, interconnected hierarchical pore network, a satisfactory percentage of heteroatom dopants, uniform distribution of Pd nanoparticles, as well as superior electrocatalytic performance metrics such as high catalytic activity, long-term stability, and tolerance to poisoning. The characterizations have confirmed the strong electrostatic interaction between the Pd nanoparticles and carbonaceous support material, thereby leading to homogeneously anchoring Pd nanoparticles onto 3D architecture and forming of novel active sites as well as synergistically boosting the EOR catalytic activity. The Pd@N,P,S-3DG has offered an enlarged electrochemically active surface area (50.3 m2 g−1), an enhanced catalytic current density of 1784 mA mg−1 Pd , and outstanding long-term stability, thereby distinctly transcending those of commercial carbonaceous material-supported Pd catalysts. The work is of great importance since it may pave the way for the rational design of low-cost high-performance carbonaceous-based nano-electrocatalysts to be utilized in large-scale energy applications. [Display omitted] • Bottom-up strategy was used to synthesize N,P,S triple-doped 3 dimensional graphene. • Pd nanoparticles were uniformly decorated onto N,P,S-3DG by solvothermal approach. • Pd@N,P,S-3D was utilized as electrocatalyst towards ethanol oxidation reaction. • Synergistic effect of heteroatoms boosted the electrocatalytic activity. • 3-dimensional network facilitated the ion transfer and reduced the resistance. [ABSTRACT FROM AUTHOR]

Direct methanol fuel cells, in which electrocatalytic oxidation of methanol takes place, are one of the most promising technologies for facilitating the shift to renewable energy sources. However, they still suffer from high-catalyst-prices, as well as sluggish kinetics of methanol oxidation reaction (MOR). Therefore, herein, palladium/Nickel(II) hydroxide/nitrogen doped reduced graphene oxide (Pd/Ni(OH)2/N-rGO) hybrid was fabricated via facile two-step solution method and utilized as electrocatalyst for MOR. The in-situ electrochemical activation pre-treatment was proposed to engineer a highly active electrocatalyst. The Pd/Ni(OH)2/N-rGO, which had distinctive structural features along with robust synergistic effects, outperformed the commercial Pd electrocatalyst in terms of catalytic activity towards MOR, with elevated anodic peak current density values. The in-situ electrochemical activation pre-treatment lead to 3.3, 3.0, and 2.0-fold increase in activity of Pd/Ni(OH)2/N-rGO, Pd/N-rGO, and Pd/C, respectively. This research lays the door for a unique technique to manufacture high-performance, low-cost electrocatalysts that might be used in fuel cell technology instead of existing Pd electrocatalysts. • Pd/Ni(OH) 2 /N-rGO ternary hybrid was synthesized by two-step solution method. • In-situ electrochemical activation method was employed to boost the MOR activity. • The catalytic activity of Pd substantially promoted by incorporation of Ni(OH) 2 clusters. • Ni(OH) 2 assisted in the oxidative removal of intermediates carbonaceous poison. • N-rGO network would serve as a catalyst support material and stabilizer. [ABSTRACT FROM AUTHOR]

[Display omitted] • The synergistic impact of Ar plasma and CrCoSb-B on electrocatalytic H 2 production activity. • The 2 min Ar plasma-treated sample exhibited soaring HER and OER activity. • CrCoSb-B catalyst outperformed the benchmark electrode under harsh industrial conditions. • CrCoSb-B (2 min)||CrCoSb-B (2 min) showed excellent performance towards UOR. Green hydrogen (H 2) is a promising fossil fuel alternative, valued for its high energy content and negligible greenhouse gas emissions. The growing demand for sustainable energy solutions necessitates cost-effective, highly efficient, and durable electrocatalysts to enable large-scale H 2 production. In our study an innovative approach by introducing a novel tri-metallic hybrid electrocatalyst, CrCoSb-B was surface treated with vacuum Ar plasma for the 1st time. This approach creates a highly efficient charge transfer within the electrocatalysts structure. Boron (B) atoms are added to expedite the water-splitting process by aiding electron transfer to the metal surfaces (Cr, Co, and Sb). On the other hand, Ar plasma treatment increases the number of active catalytic sites on the electrode surface, improving water-splitting efficiency. As a result, the CrCoSb-B electrode, subjected to 2 min Ar plasma treatment, exhibits significantly reduced overpotentials of 265 mV for hydrogen evolution reaction (HER) and 453 mV for oxygen evolution reaction (OER) at a high current density of 1000 mA/cm2 in a 1.0 M KOH electrolyte with the low Tafel values for HER and OER are 68 and 97 mV/dec, respectively. In bi-functional operation, the electrocatalyst achieves a low voltage of 2.01 V at 1000 mA/cm2 and demonstrates enhanced performance in the urea oxidation reaction (UOR) with a voltage of 1.81 V at 1000 mA/cm2. Furthermore, it maintains stability over a 24 hrs duration and nearly 100% Faradic efficiency in both H 2 and O 2 production. This research reveals a promising path for developing effective electrocatalysts, leveraging interfacial interactions and vacancies to enhance their performance in green hydrogen production. [ABSTRACT FROM AUTHOR]

Efficient water electrolysis is one of the key issues in realizing a clean and renewable energy society based on hydrogen fuel. However, several obstacles remain to be solved for electrochemical water splitting catalysts, which are the high cost of noble metals and the high overpotential of alternative catalysts. Herein, we suggest Ni-based alternative catalysts that have comparable performances with precious metal-based catalysts and could be applied to both cathode and anode by precise phase control of the pristine catalyst. A facile microwave-assisted procedure was used for NiO nanoparticles anchored on reduced graphene oxide (NiO NPs/rGO) with uniform size distribution in ~1.8 nm. Subsequently, the Ni-NiO dual phase of the NPs (A-NiO NPs/rGO) could be obtained via tailored partial reduction of the NiO NPs/rGO. Moreover, we demonstrate from systematic HADDF-EDS and XPS analyses that metallic Ni could be formed in a local area of the NiO NP after the reductive annealing procedure. Indeed, the synergistic catalytic performance of the Ni-NiO phase of the A-NiO NPs/rGO promoted hydrogen evolution reaction activity with an overpotential as 201 mV at 10 mA cm−2, whereas the NiO NPs/rGO showed 353 mV. Meanwhile, the NiO NPs/rGO exhibited the most excellent oxygen evolution reaction performance among all of the Ni-based catalysts, with an overpotential of 369 mV at 10 mA cm−2, indicating that they could be selectively utilized in the overall water splitting. Furthermore, both catalysts retained their activities over 12 h with constant voltage and 1000 cycles under cyclic redox reaction, proving their high durability. Finally, the full cell capability for the overall water electrolysis system was confirmed by observing the generation of hydrogen and oxygen on the surface of the cathode and anode.

Despite great efforts have been made during the past decade to improve the efficiency of hydrogen evolution reaction (HER) onto the MoS 2 -based electrocatalysts via increasing the number of active sites, further improvements are crucial to avoid the detachment of 2D MoS 2 nanosheets from the substrate during the long-term water splitting under intense HER. In this study, we report on the formation of highly efficient and surprisingly stable layer composed of 2D nanoplatelets from the hybrid-type MoS 2 as a new prospective electrocatalyst for HER from acidic water solution. This layer was formed via one-pot hydrothermal synthesis in the solution containing ammonium heptamolybdate, thiourea and glycine (Gly). The products obtained were characterized by SEM, HRTEM, XRD, Raman, XPS, and potential cycling. Note that at the designed hybrid-type MoS 2 /MoO 3 -Gly nanoplatelets the HER rate can achieve a stable electrochemical performance for days with ~100 mA cm−2 current density at −0.35 V potential vs RHE. Herein, highly efficient and stably working nanoporous 2D MoS 2 catalyst composed of 1T and 2H–MoS 2 phases, MoO 3 and entrapped glycine fragments was developed as effective and stably working HER electrocatalyst. Image 1 • 1T/2H–MoS 2 /MoO 3 nanostructure are developed as catalyst for HER. • Glycine is used to increase activity and stability of MoS 2 -based catalysts. • 1T/2H–MoS 2 /MoO 3 with glycine displays significantly high catalytic performance and HER stability. [ABSTRACT FROM AUTHOR]

Synergistic effects have been applied to a variety of hybrid electrocatalysts to improve their activity and selectivity. Understanding the synergistic mechanism is crucial for the rational design of these types of catalysts. Here, we synthesize a MnCo 2 O 4 /Co-N-C hybrid electrocatalyst for the oxygen reduction reaction (ORR) and systematically investigate the synergy between MnCo 2 O 4 nanoparticles and Co-N-C support. Theoretical simulations reveal that the synergy is closely related to the distance between active sites. For a pair of remote active sites, the ORR proceeds through the known 2e - + 2e - relay catalysis while the direct 4e - ORR occurs on a pair of adjacent active sites. Therefore, the formation of the undesired byproduct (H 2 O 2 ) is inhibited at the interface region between MnCo 2 O 4 and Co-N-C. This synergistic effect is further verified on an anion-exchange membrane fuel cell. The findings deepen the understanding of synergistic catalysis and will provide guidance for the rational design of hybrid electrocatalysts.

Graphical abstract Abstract Developing transition metal-based electrocatalysts with rich active sites for water electrolysis plays important roles in renewable energy fields. So far, some strategies including designing nanostructures, incorporating conductive support or foreign elements have been adopted to develop efficient electrocatalysts. Herein, we summarize recent progresses and propose in-situ electrochemical activation as a new pretreating technique for enhanced catalytic performances. The activation techniques mainly comprise facile electrochemical processes such as anodic oxidation, cathodic reduction, etching, lithium-assisted tuning and counter electrode electro-dissolution. During these electrochemical treatments, the catalyst surfaces are modified from bulk phase, which can tune local electronic structures, create more active species, enlarge surface area and thus improve the catalytic performances. Meanwhile, this technique can couple the atomic, electronic structures with electrocatalysis mechanisms for water splitting. Compared to traditional chemical treatment, the in-situ electrochemical activation techniques have superior advantages such as facile operation, mild environment, variable control, high efficiency and flexibility. This review may provide guidance for improving water electrolysis efficiencies and hold promising for application in many other energy-conversion fields such as supercapacitors, fuel cells and batteries. [ABSTRACT FROM AUTHOR]

Using inorganic-organic MoO 4 2− /aniline-pyrrole (MoO 4 2− -Polymer) hybrids nanospheres as precursors, we synthesize the porous core-shell N-doped Mo 2 C@C nanospheres with the three advantages including porous nanostructures, conductive substrate and N-doping, which may maximize the activity of electrocatalysts for hydrogen evolution reaction (HER). The as-prepared Mo 2 C@NC has the porous core-shell nanospherical structure with ultrafine Mo 2 C nanoparticles as core and ultrathin N-doped carbon (NC) nanolayers as shell. The aniline-pyrrole in MoO 4 2− -Polymer prevents fast growth and severe aggregation of Mo 2 C and form porous structure composed of ultrafine Mo 2 C, which implies the more exposed active sites. On the other hand, the carbonization of MoO 4 2− -Polymer produces the ultrathin N-doped carbon shell on the surface of Mo 2 C@NC nanospheres, which can optimize electronic structures and greatly improve charge transfer rate. Through varying MoO 4 2− content and carbonization temperature, the optimized Mo 2 C@NC sample exhibits enhanced HER performance and long-time stability both in acidic and alkaline solution. It requires an onset potential of only 110 mV and 60 mV, striking kinetic metrics (Tafel slope: 83 mV dec −1 and 70 mV dec −1 ) in 0.5 M H 2 SO 4 and in 1 M KOH, respectively. Therefore, designing unique inorganic-organic hybrid nanostructures may open up a new way for excellent electrocatalysts for HER. [ABSTRACT FROM AUTHOR]

A graphene-organic small molecule hybrid electrocatalyst (NG-TD) was prepared by a simple wet-chemical reaction between graphene oxide and the ortho-diamine-containing organic small molecule TPA-DAB. Due to the efficient doping of nitrogen atoms into the carbon-based network and the good structural restoration of the graphitic structures, NG-TD exhibits promising electrocatalytic activity for the oxygen reduction reaction (ORR) in alkaline electrolyte. Furthermore, the NG-TD hybrid electrocatalyst demonstrated additional advantages during the ORR process, such as high selectivity, excellent long-term stability, and very high resistance to methanol crossover. [ABSTRACT FROM AUTHOR]

Three-dimensional self-supported metallic structures are attractive for their unique properties of high porosity, good flexibility, large surface area per unit volume, and open-pore structure, which promote their broad application in fuel cells. Here, for the first time, a self-supported PtAuCu alloy and Pt supported over Cu2O, as two effective independent strategies, are combined into a single system, which leads to an enhanced electrochemical performance for the oxygen reduction reaction as compared to the commercial Pt/C. After cyclic voltammetry for 2000 cycles between 0.03 and 1.40 V, PtAuCu@Cu2O/Pt maintains high activity, whereas Pt/C shows a half-wave potential loss of around 20 mV. This work provides an effective strategy for rational design of highly active and stable catalysts for fuel cell applications and beyond. [ABSTRACT FROM AUTHOR]

CO 2 activation capability and conductivity of electrocatalysts are two crucial factors to address the high activation barrier and slow kinetics of CO 2 reduction reaction (CO2RR). Still, substantial promotion of both factors remains challenging. Herein, we report sulfur-deficient tin disulfide covered nitrogen-doped hollow carbon spheres (SnS 2−x /NHCS) as electrocatalyst for CO2RR. Combining experimental analysis with calculations, we demonstrate that the S vacancies and energy-level adapted coupling can decrease the reaction barrier, increase the CO 2 adsorption capacity and affinity with the intermediate, and promote the conductivity, delivering a current density of 35.3 mA cm−2 at − 1.2 V vs. reversible hydrogen electrode (RHE) and a Faradaic efficiency for formate > 80% in a large potential range from − 0.8 to − 1.2 V (vs. RHE). This work unravels the relationship of the vacancy engineering/hybrid coupling of SnS 2−x /NHCS with its CO2RR performance, and proposes a convenient route to boost the CO 2 activation capability and conductivity of electrocatalysts simultaneously. [Display omitted] • CO2RR is promoted by vacancy engineering and energy-level adapted coupling of electrocatalyst. • Enhanced conductivity, CO 2 adsorption capacity and decreased CO 2 activation barrier are achieved. • SnS 2−x /NHCS delivers a current density of 35.3 mA cm−2 at − 1.2 V vs. RHE with high durability. • A FE > 80 % for formate in a large potential range from − 0.8 to − 1.2 V vs. RHE is demonstrated. [ABSTRACT FROM AUTHOR]

The oxygen evolution reaction (OER) has attracted tremendous explorations in both fundamental and application fields recently, due to its core status in next-generation energy conversion and storage technologies, such as water splitting and metal-air batteries. Transition metal-based compounds, especially the NiFe layered double hydroxides (NiFe LDHs) have been well-established as the most effective and cost-efficient electrocatalysts to boost the sluggish water oxidation and improve the energy efficiency. Nevertheless, a favorable substrate is highly required to expose the poorly conductive active phases and enhance reactivities of OER. In this review, the recent advances concerning synthetic strategies, hierarchical structures, and OER performances of NiFe LDH/nanocarbon hybrid electrocatalysts are summarized. A brief description of OER catalysis, LDHs, and nanocarbon materials is presented firstly, followed by a thorough overview of various investigations according to their synthetic methods and structural characters. The development of high-performance OER catalysts is covered by both a short summary and a presentation of future prospects. This review provides stimulatory knowledge and sheds fresh light into the development of advanced functional materials with a wise hybridization of active phases and conductive substrates. [ABSTRACT FROM AUTHOR]

Perovskite oxides have attracted great attention recently for its high intrinsic activity in oxygen evolution reaction (OER) in electrochemical energy storage and conversion systems. However, their specific activity and durability require substantial enhancement to meet the requirement of the practical applications. Here, we demonstrate for the first time that a layered perovskite-metal oxide nano-hybrid electrocatalyst synthesized through a one-pot combustion process shows remarkably high OER activity in alkaline solution. The hybrid consists of two major phases, i.e. NiO and K 2 NiF 4 -type layered perovskite (La 0.613 Ca 0.387 ) 2 NiO 3.562 , showing synergistically enhanced OER activity and excellent durability under harsh OER operating conditions. The NiO–(La 0.613 Ca 0.387 ) 2 NiO 3.562 hybrid exhibits the lowest Tafel slope (~42 mV dec −1 ) and highest mass activity (52.2 mA mg −1 @ 1.63 V vs RHE) among all catalysts studied including noble metal oxide RuO 2 and well-known perovskite Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3− δ . [ABSTRACT FROM AUTHOR]

To replace the existing noble-metal-based catalysts, developing highly efficient, stable electrocatalysts for oxygen reduction reactions for the increased current generation with lower overpotential is a demanding undertaking. In the present work, CuO–NiO/rGO nanocomposites were prepared using simple, cost-effective Co-precipitation methods. They act as highly effective electrocatalysts for oxygen reduction reactions in an alkaline medium. The structural characterizations demonstrate that prepared nanoparticles (≈13 nm) are tightly and effectively organized on reduced graphene oxide sheets. The electrochemical properties of the CuO, NiO nanoparticles and CuO–NiO, CuO–NiO/rGO nanocomposites were investigated. The results of the CuO–NiO/rGO nanocomposites revealed the high current density (2.9 × 10−4 mA cm−2), lower Tafel slope (72 mV dec−1) and low hydrogen peroxide yield (15%) when compared to other prepared materials (CuO, NiO, and CuO–NiO). The reduced graphene oxide increases an electron transfer during the ORR process, while the CuO–NiO has variable oxidation states that promote electro-rich features. With the combination of CuO–NiO and rGO, the hybrid electrocatalysts specific surface area and charge transfer rate drastically increase. The investigations of the rotating ring-disk electrodes experiments indicate that the oxygen reduction process takes place on CuO–NiO/rGO through an efficient four-electron pathway. Our results propose a new approach to creating highly efficient and long-lasting electrocatalysts. Combining CuO–NiO nanoparticles with an rGO sheet was tested as an ORR electrocatalyst. [Display omitted] • The CuO–NiO incorporation of Reduced graphene oxide is synthesized by a Co-precipitation. • The CuO–NiO/rGO nanocomposites electrocatalysis shows four electrons transform process. An excellent current density and increased on set potential. • CuO–NiO nanoparticles have a synergistic effect on the rGO sheet, leading to higher ORR activity on this noble metal-free catalyst. [ABSTRACT FROM AUTHOR]

Pt single-atom materials possess an ideal atom economy but suffer from limited intrinsic activity and side reaction of producing H 2 O 2 in catalyzing the oxygen reduction reaction (ORR); platinum alloys have higher intrinsic activity but weak stability. Here, we demonstrate that anchoring platinum alloys on single-atom Pt-decorated carbon (Pt-SAC) surmounts their inherent deficiencies, thereby enabling a complete four-electron ORR pathway catalysis with high efficiency and durability. Pt 3 Co@Pt-SAC demonstrates an exceptional mass and specific activities 1 order of magnitude higher than those of commercial Pt/C. They are durable throughout 50000 cycles, showing only a 10 mV decay in half-wave potential. An in situ Raman analysis and theoretical calculations reveal that Pt 3 Co core nanocrystals modulate electron structures of the adjacent Pt single atoms to facilitate the intermediate absorption for fast kinetics. The superior durability is attributed to the shielding effect of the Pt-SAC coating, which significantly mitigates the dissolution of Pt 3 Co cores. The hybridizing strategy might promote the development of highly active and durable ORR catalysts.

Abstract: Pt/C/MnO2 hybrid catalysts were prepared by a wet chemical method. Pt/C electrocatalysts were treated with manganese sulfate monohydrate (MnSO4·H2O) and sodium persulfate (Na2S2O8) to produce MnO2. The presence of MnO2 was confirmed by FTIR spectroscopy. Rotating ring–disk electrode (RRDE) experiments were performed on electrodes prepared using the hybrid electrocatalysts to estimate the amount of hydrogen peroxide (H2O2) formed during the oxygen reduction reaction (ORR) as a function of MnO2 content. Pt/C/MnO2 (5% by weight of MnO2) hybrid electrocatalysts produced 50% less hydrogen peroxide than the baseline Pt/C electrocatalyst. The hybrid electrocatalysts were used to prepare membrane electrode assemblies that were tested at 90°C and 50% RH at open circuit with pure hydrogen as fuel and air as the oxidant. The fluoride ion concentration was measured using an ion selective electrode. The concentration of F− in the anode condensate over 24h was found to be reduced by a factor of 3–4 when Pt/C/MnO2 replaced Pt/C as the catalyst. Through cyclic voltammetry and RRDE kinetic studies, the lower ORR activity of the acid treated hybrid electrocatalysts was attributed to catalyst treatment with acid during MnO2 introduction. The activity of the hybrid catalyst was improved by switching to a water-based synthesis. [Copyright &y& Elsevier]

Measurement of signal molecule is critically important for understanding living systems. Nitric oxide (NO) is a key redox signal molecule that shows diverse roles in virtually all life forms. However, probing into NO's activities is challenging as NO has restricted lifetime (<10 s) and limited diffusion distance (usually <200 μm). So, for the direct acupuncture of NO within the time-space resolution, an electrochemical microsensor has been designed and fabricated in this work. Fabrication of the microsensor is achieved by (1) selective assembly of an electrocatalytic transducer, (2) attaching the transducer on carbon fiber electrode, and (3) covered it with a screen layer to reduce signal interference. The fabricated microsensor exhibits high sensitivity (LOD, 13.5 pM), wide detection range (100 pM–5 μM), and good selectivity. Moreover, studies have revealed that the availability of the sensor for efficient detection of NO is due to the formation of a specific DNA/porphyrin hybrid structure that has synergetic effects on NO electrocatalysis. Therefore, NO release by cells and tissues can be directly and precisely traced, in which we have obtained the release pattern of NO by different cancer cell lines, and have known its dynamics in tumor microenvironment. The fabricated electrocatalytic microsensor may provide a unique and useful tool for the direct assay of NO with high time-space resolution, which promisingly gives a technical solution for the bioassay of NO in living systems. • An electrochemical microsensor is fabricated for direct assay of nitric oxide (NO). • The assembled DNA-G4/porphyrin hybrid represents a favorably electrocatalytic transducer for NO. • Excellent analytical performance is achieved, with picomolar detection limit and broad detection range. • High time-space detection is shown both in cancer cell lines and tumor microenvironment. [ABSTRACT FROM AUTHOR]

Efficient water electrolysis is one of the key issues in realizing a clean and renewable energy society based on hydrogen fuel. However, several obstacles remain to be solved for electrochemical water splitting catalysts, which are the high cost of noble metals and the high overpotential of alternative catalysts. Herein, we suggest Ni-based alternative catalysts that have comparable performances with precious metal-based catalysts and could be applied to both cathode and anode by precise phase control of the pristine catalyst. A facile microwave-assisted procedure was used for NiO nanoparticles anchored on reduced graphene oxide (NiO NPs/rGO) with uniform size distribution in ~1.8 nm. Subsequently, the Ni-NiO dual phase of the NPs (A-NiO NPs/rGO) could be obtained via tailored partial reduction of the NiO NPs/rGO. Moreover, we demonstrate from systematic HADDF-EDS and XPS analyses that metallic Ni could be formed in a local area of the NiO NP after the reductive annealing procedure. Indeed, the synergistic catalytic performance of the Ni-NiO phase of the A-NiO NPs/rGO promoted hydrogen evolution reaction activity with an overpotential as 201 mV at 10 mA cm−2, whereas the NiO NPs/rGO showed 353 mV. Meanwhile, the NiO NPs/rGO exhibited the most excellent oxygen evolution reaction performance among all of the Ni-based catalysts, with an overpotential of 369 mV at 10 mA cm−2, indicating that they could be selectively utilized in the overall water splitting. Furthermore, both catalysts retained their activities over 12 h with constant voltage and 1000 cycles under cyclic redox reaction, proving their high durability. Finally, the full cell capability for the overall water electrolysis system was confirmed by observing the generation of hydrogen and oxygen on the surface of the cathode and anode. [ABSTRACT FROM AUTHOR]

The use of water splitting has been investigated as a good alternate for storing electrical energy. While the general interest in developing non-toxic, high-performance, and economically feasible catalysts for oxygen evolution reaction (OER) is noteworthy, there is also significant interest in water splitting research. Recently, perovskite-type oxides have performed as an alternative to non-precious metal catalysts and can act as a new class of effective catalysts in water splitting systems. Herein, a perovskite-structured FeTiO3 was prepared via a facile one-step solvothermal method using ionic liquid as templates. The results of structural and morphological studies have supported the formation of FeTiO3 perovskite. Furthermore, FeTiO3 perovskite demonstrated OER activity with a lower onset potential of 1.45 V vs. RHE and Tafel slope value of 0.133 V.dec−1 at 1 M KOH solution using mercury/mercurous oxide (Hg/HgO) were used as working electrodes. [ABSTRACT FROM AUTHOR]

A promising bifunctional overall water splitting electrocatalyst consisting of novel 2D foam-like porous N,P-doped carbon nanosheets directly immobilized NiCo nanoalloy has been developed via a feasible and scalable hydrogel-bridged pyrolysis strategy. Both experimental and theoretical studies illustrate that the extraordinary activity of the NiCo@N,P-CNSs attributed to both thermodynamic and kinetic aspects, that is, abundant firmly-confined NiCo nanoparticles, highly porous nanosheet nanoarchitecture and favorable Gibbs free energies for hydrogen and water adsorption. • Hydrogel-bridged strategy was proposed to construct 2D foam-like porous carbon nanohybrid. • NiCo nanoparticles immobilized firmly in N,P-codoped carbon nanosheets. • The as-synthesized catalyst demonstrated excellent bifunctional HER and OER performance. • DFT calculations corroborate that the NiCo alloy possesses favorable Gibbs free energies. The rational design of earth-abundant and high-efficiency bifunctional electrocatalysts for expediting the sluggish kinetics of both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is imperative to fulfill the sustainable hydrogen-based energy electrochemical devices. The design rationale for advanced catalyst requires to simultaneously take into account both thermodynamic and kinetic aspects. Herein, a feasible and scalable hydrogel-bridged pyrolysis strategy is developed to directly immobilize uniform NiCo nanoparticles into 2D foam-like porous N,P-codoped carbon nanosheets (abbreviated as NiCo@N,P-CNSs hereafter). The bimetallic alloy synergy, well confined active sites and highly porous nanosheet architecture collaboratively afford modulated electronic structure, abundant active sites, and multidimensional mass diffusion pathways, which are thermodynamically and kinetically favorable for catalytic performance. Consequently, the as-fabricated NiCo@N,P-CNSs exhibit distinguished bifunctional performance in alkaline medium, requiring overpotentials of only 99 and 226 mV at a current density of 10 mA cm−2 for HER and OER, respectively. Furthermore, when equipped in a two-electrode electrolyzer, the NiCo@N,P-CNS electrode couple displays a low cell voltage of 1.57 V at 10 mA cm−2 and outstanding stability, outperforming a majority of the recently reported non-precious electrocatalysts and representing a competitive candidate for practical water electrolysis. Density functional theory (DFT) simulations further corroborate that the bimetallic NiCo alloy possesses favorable Gibbs free energies of water and hydrogen adsorption, which are beneficial for enhancing its intrinsic activity. More importantly, the developed methodology for the simultaneous realization of electronic modulation, nanostructure engineering and nanocarbon hybridization may provide new perspectives for future exploration of high-efficiency electrocatalysts for a range of energy conversion applications and beyond. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of carbon dioxide (CO 2) to value-added fuels and chemicals provides an alternative way to realize sustainable carbon recycling. Developing robust electrocatalysts with high activity and selectivity is critically important for achieving efficient electrochemical CO 2 reduction reaction (CO 2 RR). Hybrid electrocatalysts with the catalytically active species ranging from atomic scale to nanoscale (single atoms, nanoclusters, and nanoparticles) anchored on functional supports have demonstrated encouraging catalytic activity for a variety of catalysis applications. Particularly, manipulating metal-support interface chemistry has been regarded as one of the most efficient strategies to optimize the catalytic performance of hybrid catalysts, and is becoming an emerging research frontier in the catalysis filed. In this review, we summarized the recent progress on hybrid electrocatalysts towards efficient CO 2 RR with a focus on strategies for manipulating the metal-support interaction. In this regard, the approaches for tuning metal-support interaction were discussed in detail from three aspects: metal active species, functional supports, and treatments of electrocatalysts. The relevant fundamentals for CO 2 RR, including reaction mechanisms and crucial parameters, are also comprehensively discussed. Finally, the research challenges are highlighted and perspectives are proposed towards rational design of robust electrocatalysts for CO 2 RR. The recent progress on hybrid electrocatalysts for efficient electrochemical CO 2 reduction reaction (CO 2 RR) are summarized with a focus on strategies for manipulating the metal-support interface chemistry. This review will not only provide new insights into designing robust CO 2 RR electrocatalysts, but also shed light on developing hybrid electrocatalysts towards a wide range of electrocatalysis applications. ga1 • The recent progress on hybrid electrocatalysts towards efficient CO 2 RR is summarized. • The review is focused on strategies for manipulating metal-support interface chemistry. • This review will provide new insights into designing robust CO 2 RR electrocatalysts. • This review will shed light on developing hybrid electrocatalysts towards other electrocatalysis applications. [ABSTRACT FROM AUTHOR]

Nanomaterials are being widely considered as electrocatalyst for the production of hydrogen nowadays. Due to their outstanding catalytic performance, research activities are ongoing to explore the efficient electrocatalyst. This review article will be focused on recent challenges and progression in developing the metal and metal-free electrocatalyst for HER/OER activity. • Mechanisms of HER and OER reaction in both acidic and alkaline medium were discussed. • Multi-metallic alloy, oxides and hydroxides are promising electrocatalyst for HER/OER. • Nanomaterials having amorphous structure possess better catalytic efficiency. • Transitional metal doped MOFs are found to be more promising for HER activity. Electrocatalytic water splitting is considered being an optimistic process and can be a sustainable source of renewable energy for the future. Although, the primary overpotential requirement and stability problem of the electrocatalysts make the process difficult for industrial applications, a cost-effective electrocatalyst with high surface area, stability, and bifunctional activity can eliminate such barriers in the upcoming eons. To date, metal alloys, metal hydroxides, metal oxides, metal derivatives (phosphides, sulfides, selenides, and carbides) metal–organic frameworks, hybrid and metal-free materials based electrocatalysts have been already developed for the overall water splitting. Herein, the challenges to enhance the activity, stability and durability in the metal (both noble metal and transitional metal) and metal-free based electrocatalyst for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are summarized. A general overview of the water splitting mechanism followed by various electrocatalyst are discussed mainly. Moreover, it is expected to provide a comprehensive summary and outlook at the end. [ABSTRACT FROM AUTHOR]

• V 8 C 7 /CoP were prepared through pyrolysis and a subsequent phosphidation. • V 8 C 7 /CoP exhibits a splendid electrocatalytic activity toward HER, OER and UOR. • A V 8 C 7 /CoP-AAAE was set up for energy-saving electrolytic hydrogen production. Hydrogen production via water electrolysis for large scale application is still limited majorly by the huge energy consumption and high cost of catalyst materials. In this work, with rationally designing V/Co metal-organic framework (V/Co-MOF) as a precursor, a series of V 8 C 7 decorating CoP nanosheets-assembled microspheres (V 8 C 7 /CoP) was synthesized via pyrolysis and a subsequent phosphidation. Thanks to the synergistic effect between V 8 C 7 and CoP, the optimized V 8 C 7 /CoP as trifunctional catalysts exhibit remarkable performance toward hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and urea oxidation reaction (UOR). More importantly, we propose an acid-alkaline asymmetric-electrolyte electrolyzer (AAAE) by using the optimized V 8 C 7 /CoP electrode as both acidic cathode for HER and alkaline anode UOR, respectively. The optimum AAAE system only needs an applied voltage of 0.8 V to reach an electrolytic current density of 10 mA cm−2 for hydrogen production, which significantly reduces the energy consumption for hydrogen production owing to the assistance of electrochemical neutralization energy (ENE) and electrochemical urea oxidation energy. [ABSTRACT FROM AUTHOR]

Hydrogen energy is one of the key technologies that can help to prevent global warming. A water electrolysis process can be used to produce hydrogen, in which hydrogen is produced at one electrode of the electrochemical cell, and oxygen is produced at the other electrode. On the other hand, the oxygen evolution reaction (OER) requires multiple reaction steps and precious-metal-based catalysts (e.g., Ru/C, Ir/C, RuO2, and IrO2) as electrocatalysts to improve the reaction rate. Their high cost and limited supply, however, limit their applications to the mass production of hydrogen. In this study, boron, nitrogen-doped carbon incorporated with molybdenum carbide (MoC-BN/C) was synthesized to replace the precious-metal-based catalysts in the OER. B, N-doped carbon with nanosized molybdenum nanoparticles was fabricated by plasma engineering. The synthesized catalysts were heat-treated at 600, 700, and 800 °C in nitrogen for one hour to enhance the conductivity. The best MoC-BN/C electrocatalysts (heated at 800 °C) exhibited superior OER catalytic activity: 1.498 V (vs. RHE) and 1.550 V at a current density of 10 and 100 mA/cm2, respectively. The hybrid electrocatalysts even outperformed the noble electrocatalyst (5 wt.% Ru/C) with higher stability. Therefore, the hybrid electrocatalyst can replace expensive precious-metal-based catalysts for the upcoming hydrogen economy. [ABSTRACT FROM AUTHOR]

• A novel nonenzymatic sensor of Au-Cu x S/3DCF was prepared for glucose detection. • The sensor detects glucose with good sensitivity and low LOD of 7.62 μM. • The sensor detects glucose with wide linear detection range of 1.98–976.56 μM. • The sensor exhibited good durability, selectivity as well as excellent stability. In this study, we developed a sensitive glucose sensor by hybridizing abundant gold nanoparticles on surface of copper sulfide nanosheets supported three-dimensional framework. The sensor showed high activity and long-term stability towards glucose oxidation. In this context, is was recognized an adequate sensitivity of 0.059 mA μM−1 cm-2, wide linear detection range of 1.98–976.56 μM, along with low LOD of 7.62 μM. Besides, the sensor also presented high selectivity and good retention of around 85.9% after long-term operation of 1800s. These results may be assumed to the synergistic effects produced by the combination between gold nanoparticles and copper sulfide nanosheets, as well as the formation of hierarchical 3D architecture, which promoted electroactive surface area, charge transfer, electrolyte penetration, and ion diffusion, thereby leading to the enhancement of catalytic activity. Our work may open a new option for developing highly catalytic material for glucose sensor in analytical purposes. [ABSTRACT FROM AUTHOR]

An effective non-precious bare NiCo 2 O 4 (NCO) micro-shrubs and graphene (rGO) supported hybrid catalysts (NCO/rGO) were prepared by a simple urea assisted one-pot hydrothermal route. The authors were motivated to investigate an influence of synergistic effect between NCO nanoparticles and rGO sheets of freshly prepared hybrid catalysts (NCO/rGO) by adjusting the starting metal (nickel & cobalt nitrate hexahydrate) precursors, which has been denoted as 50 NCO/rGO, 100 NCO/rGO & 150 NCO/rGO in the present work. All the freshly prepared rGO, NCO and rGO supported hybrid catalysts with three different NCO mass loading samples were characterized through different characterization techniques such as XRD, FT-Raman, HR-SEM, HR-TEM, LSV, CV and galvanostatic charge/discharge studies, respectively. Among them, the rGO supported hybrid catalyst with lower amount of NCO mass loading (50 NCO/rGO) exhibits an outstanding oxygen reduction reaction (ORR) activity with lower onset potential, high limiting current density via. four-electron mechanism in an O 2 -saturated 0.1 M KOH electrolyte solution at room temperature. In addition, the specific capacitance of hybrid electrode is found to be 1305 F g-1 at a scan rate of 5 mV s−1 with 89% retention of cyclic stability even after 3000 cycles. The observed electrocatalytic activity and capacitive performances of an optimized hybrid sample (50 NCO/rGO) is strongly indicates an influence of better synergistic effect between NCO nanoparticles and rGO nanosheets. Hence, an optimized rGO supported hybrid catalyst (50 NCO/rGO) could be a promising electrocatalyst as well as hybrid electrode for metal-air batteries and supercapacitor applications, respectively. Image 1 • An effective non-precious bare NiCo 2 O 4 (NCO) micro-shrubs and graphene (rGO) supported hybrid catalysts (NCO/rGO) with three different NCO mass loading samples were prepared by a simple urea assisted one-pot hydrothermal route. • Investigation an influence of synergistic effect between NCO nanoparticles and rGO sheets with three different NCO mass loadings by adjusting the starting metal (nickel & cobalt nitrate hexahydrate) precursors in the hybrid catalysts. • The hybrid catalyst with lower amount of NCO mass loading (50 NCO/rGO) exhibits an outstanding oxygen reduction reaction (ORR) activity with lower onset potential, high limiting current density via. four-electron mechanism in an O 2 -saturated 0.1 M KOH electrolyte solution at room temperature, owing to the occurrence of better synergistic effect. • The specific capacitance of hybrid 50 NCO/rGO electrode is found to be 1305 F g-1 at a scan rate of 5 mV s−1 with 89% retention of cyclic stability even after 3000 cycles. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) have emerged as a promising class of materials. However, their insulating nature has limited their application as electrocatalysts. Herein, we report a heterogeneous nanostructure of a Ni-based MOF-modified Ni 3 S 2 /NiS hollow nanoparticle. The Ni 3 S 2 /NiS hollow core is prepared by a sulfuration process from a colloidal nickel nanoparticle using dodecanethiol followed by a low-temperature heat treatment in air to remove the adsorbed organic ligands. The thin shell of the Ni-based MOF (Ni-BDC) is synthesized using an in situ method in which the nickel sulfides supply the metal source and the additional terephthalic acid serves as the linker. Serving as an oxygen evolution reaction catalyst, this hybrid nanocomposite shows superior electrocatalytic performance with a low overpotential of 298 mV at 10 mA·cm -2 without carbon addition and a long-time endurability with no detectable activity deterioration, which can be attributed to the synergistic effect of the advantageous heterogeneous structure, combining the good hydrophilicity and coordinative unsaturation of the Ni-BDC shell and the high conductivity and porosity of the Ni 3 S 2 /NiS core as well as the strongly coupled interface between them.

On page 473, Q. Zhang and co‐workers review advances in hybrid electrocatalysts concerning synthetic strategies, structural characters, and fundamental insights into the structure‐performance relationship for the oxygen evolution reaction. [ABSTRACT FROM AUTHOR]

The development of nonprecious metal based electrocatalysts for hydrogen evolution reaction (HER) has received increasing attention over recent years. Previous studies have established Mo 2 C as a promising candidate. Nevertheless, its preparation requires high reaction temperature, which more than often causes particle sintering and results in low surface areas. In this study, we show supporting Mo 2 C nanoparticles on the three-dimensional scaffold as a possible solution to this challenge and develop a facile two-step preparation method for ∼3 nm Mo 2 C nanoparticles uniformly dispersed on carbon microflowers (Mo 2 C/NCF) via the self-polymerization of dopamine. The resulting hybrid material possesses large surface areas and a fully open and accessible structure with hierarchical order at different levels. MoO 4 2- was found to play an important role in inducing the formation of this morphology presumably via its strong chelating interaction with the catechol groups of dopamine. Our electrochemical evaluation demonstrates that Mo 2 C/NCF exhibits excellent HER electrocatalytic performance with low onset overpotentials, small Tafel slopes, and excellent cycling stability in both acidic and alkaline solutions.