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In both the manufacturing and chemical industries, benzoquinone is a crucial chemical product. A perfect and economical method for making benzoquinone is the electrochemical oxidation of phenol, thanks to the traditional thermal catalytic oxidation of phenol process requires high cost, serious pollution and harsh reaction conditions. Here, a unique heterostructure electrocatalyst on nickel foam (NF) consisting of nickel sulfide and nickel oxide (Ni9S8‐Ni15O16/NF) was produced, and this catalyst exhibited a low overpotential (1.35 V vs. RHE) and prominent selectivity (99 %) for electrochemical phenol oxidation reaction (EOP). Ni9S8‐Ni15O16/NF is beneficial for lowering the reaction energy barrier and boosting reactivity in the EOP process according to density functional theory (DFT) calculations. Additionally, an alkali/acid hybrid flow cell was successfully established by connecting Ni9S8‐Ni15O16/NF and commercial RuIr/Ti in series to catalyze phenol oxidation in an alkaline medium and hydrogen evolution in an acid medium, respectively. A cell voltage of only 0.60 V was applied to produce a current density of 10 mA cm−2. Meanwhile, the system continued to operate at 0.90 V for 12 days, showing remarkable long‐term stability. The unique configuration of the acid‐base hybrid flow cell electrolyzer provides valuable guidance for the efficient and environmentally friendly electrooxidation of phenol to benzoquinone. [ABSTRACT FROM AUTHOR]

The development of precious‐metal alternative electrocatalysts for oxygen reduction reaction (ORR) is highly desired for a variety of fuel cells, and single atom catalysts (SACs) have been envisaged to be the promising choice. However, there remains challenges in the synthesis of high metal loading SACs (>5 wt.%), thus limiting their electrocatalytic performance. Herein, a facile self‐sacrificing template strategy is developed for fabricating Co single atoms along with Co atomic clusters co‐anchored on porous‐rich nitrogen‐doped graphene (Co SAs/AC@NG), which is implemented by the pyrolysis of dicyandiamide with the formation of layered g‐C3N4 as sacrificed templates, providing rich anchoring sites to achieve high Co loading up to 14.0 wt.% in Co SAs/AC@NG. Experiments combined with density functional theory calculations reveal that the co‐existence of Co single atoms and clusters with underlying nitrogen doped carbon in the optimized Co40SAs/AC@NG synergistically contributes to the enhanced electrocatalysis for ORR, which outperforms the state‐of‐the‐art Pt/C catalysts with presenting a high half‐wave potential (E1/2 = 0.890 V) and robust long‐term stability. Moreover, the Co40SAs/AC@NG presents excellent performance in Zn–air battery with a high‐peak power density (221 mW cm−2) and strong cycling stability, demonstrating great potential for energy storage applications. [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]

The continuously increasing CO2 released from human activities poses a great threat to human survival by fluctuating global climate and disturbing carbon balance among the four reservoirs of the biosphere, earth, air, and water. Converting CO2 to value-added feedstocks via electrocatalysis of the CO2 reduction reaction (CO2RR) has been regarded as one of the most attractive routes to re-balance the carbon cycle, thanks to its multiple advantages of mild operating conditions, easy handling, tunable products and the potential of synergy with the rapidly increasing renewable energy (i.e., solar, wind). Instead of focusing on a special topic of electrocatalysts for the CO2RR that have been extensively reviewed elsewhere, we herein present a rather comprehensive review of the recent research progress, in the view of associated value-added products upon selective electrocatalytic CO2 conversion. We initially provide an overview of the history and the fundamental science regarding the electrocatalytic CO2RR, with a special introduction to the design, preparation, and performance evaluation of electrocatalysts, the factors influencing the CO2RR, and the associated theoretical calculations. Emphasis will then be given to the emerging trends of selective electrocatalytic conversion of CO2 into a variety of value-added products. The structure-performance relationship and mechanism will also be discussed and investigated. The outlooks for CO2 electrocatalysis, including the challenges and opportunities in the development of new electrocatalysts, electrolyzers, the recently rising operando fundamental studies, and the feasibility of industrial applications are finally summarized. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrogen reduction reaction (NRR) plays a vital role for next‐generation electrochemical energy conversion technologies. However, the NRR kinetics is still limited by the sluggish hydrogenation process on noble‐metal‐free electrocatalyst. Herein, we report the rational design and synthesis of a hybrid catalyst with atomic iron sites anchored on a N,O‐doped porous carbon (FeSA‐NO‐C) matrix of an inverse opal structure, leading to a remarkably high NH3 yield rate of 31.9 μgNH3 h−1 mg−1cat. and Faradaic efficiency of 11.8 % at −0.4 V for NRR electrocatalysis, outperformed almost all previously reported atomically dispersed metal‐nitrogen‐carbon catalysts. Theoretical calculations revealed that the observed high NRR catalytic activity for the FeSA‐NO‐C catalyst stemmed mainly from the optimized charge‐transfer between the adjacent O and Fe atoms homogenously distributed on the porous carbon support, which could not only significantly facilitate the transportation of N2 and ions but also effectively decrease the binding energy between the isolated Fe atom and *N2 intermediate and the thermodynamic Gibbs free energy of the rate‐determining step (*N2 → *NNH). [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) monometallic pnictogens (antimony or Sb, and bismuth or Bi) nanosheets demonstrate potential in a variety of fields, including quantum devices, catalysis, biomedicine and energy, because of their unique physical, chemical, electronic and optical properties. However, the development of general and high‐efficiency preparative routes toward high‐quality pnictogen nanosheets is challenging. A general method involving a molten‐salt‐assisted aluminothermic reduction process is reported for the synthesis of Sb and Bi nanosheets in high yields (>90 %). Electrocatalytic CO2 reduction was investigated on the Bi nanosheets, and high catalytic selectively to formate was demonstrated with a considerable current density at a low overpotential and an impressive stability. Bi nanosheets continuously convert CO2 into formate in a flow cell operating for one month, with a yield rate of 787.5 mmol cm−2 h−1. Theoretical results suggest that the edge sites of Bi are far more active than the terrace sites. [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]

We report a straightforward strategy to design efficient N doped porous carbon (NPC) electrocatalyst that has a high concentration of easily accessible active sites for the CO2 reduction reaction (CO2RR). The NPC with large amounts of active N (pyridinic and graphitic N) and highly porous structure is prepared by using an oxygen‐rich metal–organic framework (Zn‐MOF‐74) precursor. The amount of active N species can be tuned by optimizing the calcination temperature and time. Owing to the large pore sizes, the active sites are well exposed to electrolyte for CO2RR. The NPC exhibits superior CO2RR activity with a small onset potential of −0.35 V and a high faradaic efficiency (FE) of 98.4 % towards CO at −0.55 V vs. RHE, one of the highest values among NPC‐based CO2RR electrocatalysts. This work advances an effective and facile way towards highly active and cost‐effective alternatives to noble‐metal CO2RR electrocatalysts for practical applications. [ABSTRACT FROM AUTHOR]

Development of cost‐effective and highly efficient oxygen evolution reaction (OER) electrocatalysts has become a vital project of renewable energy technologies. The OER is critical for a variety of electrochemical energy devices such as water electrolyzers, metal‐air batteries, CO2 reduction, and electrosynthesis of ammonia. Compared to extensively studied metal oxide catalysts, graphitized carbon catalysts have been newly emerged as promising OER catalysts especially in less corrosive alkaline media, due to their low cost, high electrical conductivity, unique physicochemical properties, and excellent electrocatalytic performances. In this review, we discussed recent advances in nanostructured carbon electrocatalysts. At first, metal‐free OER carbon electrocatalysts including single‐ and multi‐heteroatom doping and edge‐ and defect‐rich defects are introduced. Then, transition metal and heteroatom co‐doped nanocarbons are summarized including Co−N−C, Ni−N−C, and Fe‐N−C. In addition, carbon based hybrid electrocatalysts are highlighted, which include carbon based transition metal nitrides (TMNx), sulfides (TMSx), and selenides (TMSex), and phosphides (TMPx). Finally, current challenges and perspective for future research on carbon‐based OER catalysts are outlined. [ABSTRACT FROM AUTHOR]

Developing highly efficient electrocatalysts for selective glycerol oxidation reaction (GOR) is crucial to implement biomass valorization and to advance the energy conversion efficiency of glycerol fuel cells. Herein, a hybrid alkali-acid direct glycerol fuel cell (DGFC) that can not only deliver a high power density but also enable glycerol valorization conversion is demonstrated. Such double-benefits electrochemical device is implemented by in situ growth of FeCoNiCrMnS 2 nanoparticles on carbon cloth (FeCoNiCrMnS 2 /CC) as anode, which exhibits high activity and selectivity for GOR with low overpotential and high Faradaic efficiency toward the formate product. Based on the results of finite element method simulations of element distribution on FeCoNiCrMnS 2 , the electrocatalytic sites was investigate by density functional theory in conjunction with Monte Carlo and machine learning simulations and confirmed that the desired catalytic properties primarily originate from the Ni and Co sites, while Cr and Mn optimized the electronic structure of these sites. The as-developed DGFC can release a maximum peak power density of 50.1 mW cm−2 and stably generate formate with high selectivity. The present work may inspire to contrive the newly advanced energy device and provide fresh impetus for the development of newly high-entropy materials for a variety of application. [Display omitted] • High-entropy alloy electrocatalysts of FeCoNiCrMnS 2 is developed for glycerol oxidation • The hybrid acid/alkali DGFC is proposed to simultaneously produce electricity and upgrade glycerol • The fuel cell can produce formate with an FE of exceeding 90 % and release a peak power density of 50.1 mW cm−2 • Combining DFT with MC and ML simulations unveil the crucial role of multiple elements in electrocatalysis [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]

Abstract: Developing cost‐effective electrocatalysts for high‐selectivity CO2 electroreduction remains challenging. We herein report a perfluorinated covalent triazine framework (CTF) electrocatalyst that displays very high selectivity in the electroreduction of CO2 to CH4 with a faradaic efficiency of 99.3 % in aqueous electrolyte. Systematic characterization and electrochemical studies, in combination with density functional theory calculations, demonstrate that the presence of both nitrogen and fluorine in the CTF provides a unique pathway that is inaccessible with the individual components for CO2 electroreduction. [ABSTRACT FROM AUTHOR]

Abstract: Hybrids of Fe/Fe3C embedded in N‐doped carbon nanotubes (Fe/Fe3C@NCNTs) are prepared by pyrolyzing mixtures of Fe3O4 nanoparticles and dicyandiamide. The systematic electrochemical study of Fe/Fe3C@NCNTs shows a decent catalytic activity toward the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR). The sample of Fe/Fe3C@NCNTs at 750 °C exhibits a remarkably high activity with an onset potential of 1.47 V for the OER, and an onset potential of 0.96 V and half‐wave potential 0.88 V for the ORR, which inspired us to set up a rechargeable Zn‐air battery with such Fe/Fe3C@NCNT nanohybrids as the cathode materials, showing a maximum power density of 198 mW cm−2 and long‐term stability after 500 cycles. We also demonstrate that Fe/Fe3C@NCNTs present favorable electrocatalytic activity towards the CO2 reduction reaction (CO2RR) with a low onset potential and good selectivity. The major products are a mixture of H2 and CO gases that can be used for methanol production in the Fischer−Tropsch process. [ABSTRACT FROM AUTHOR]

Nanohybrids with hollow CoNiP nanoparticles decorating reduced graphene oxide (h-CoNiP/rGO) are prepared by a low-temperature phosphorization method. The h-CoNiP/rGO present favorable electrocatalytic advantages toward the oxygen evolution reaction (OER) in alkaline solution, including an onset potential of 1.44 V, a low overpotential of 280 mV at a current density of 10 mA cm − 2 , a small Tafel slope of 65.2 mV dec − 1 , and pretty good durability. The use of earth-abundant elements in a high-activity OER electrocatalyst may provide an effective way of advancing the development of full water splitting. [ABSTRACT FROM AUTHOR]

The daunting challenge in electrochemical conversion of CO 2 into carbon resource is to explore high-activity and high-selectivity electrocatalysts for CO 2 reduction reaction (CO 2 RR). Here, we report a water-bath route for tunable synthesis of a set of CuO nanostructures including nanowires (NWs), microsphere and nanoflake. The CuO NWs show a unique one-dimensional (1D) structure constructed by nanoparticles building block and manifest a significantly enhanced electrochemical surface area compared with the counterparts and the bulk CuO. Systematic electrochemical studies demonstrate the CuO NWs, as electrocatalyst of CO 2 RR, manifests a highly electrocatalytic activity, as demonstrated by reaching a current dentistry of 2 mA cm −2 at a relative low onset potential and delivering a catalytic current density of up to 100 mA cm −2 at −1.6 V. The nanoparticles assembled 1D structure provides a large amount of edge active sites and thus contributes to such a high electrocatalytic activity. Besides a small quantity of HCOOH, the major products of CO 2 RR are H 2 , CO, with tunable ratio of H 2 /CO in the range of 1.75:1 to 2.75:1 depending on the applied potential; such H 2 /CO mixture product are potentially used for the syngas that are key feedstocks to produce a variety of liquid fuels in industry. [ABSTRACT FROM AUTHOR]

A novel OER electrocatalyst, namely oxygen-incorporated amorphous cobalt sulfide porous nanocubes (A-CoS4.6O0.6 PNCs), show advantages over the benchmark RuO2 catalyst in alkaline/neutral medium. Experiments combining with calculation demonstrate that the desirable O* adsorption energy, associated with the distorted CoS4.6O0.6 octahedron structure and the oxygen doping, contribute synergistically to the outstanding electrocatalytic activity. [ABSTRACT FROM AUTHOR]

A facile recipe has been developed to prepare three-dimensional nanoarchitectures of nitrogen-doped graphene loading Co nanoparticle hybrids (Co/NG). The hybrids show an outstanding electrocatalytic activity for glucose oxidation reaction (GOR) and oxygen reduction reaction (ORR), and thus can be used as electrode materials of a nonenzymatic and precious-metal-free glucose fuel cell (GFC). [ABSTRACT FROM AUTHOR]

On page 872 novel nitrogen‐doped graphene/cobalt‐embedded porous carbon polyhedron hybrid electrocatalyst is obtained by Z. H. Wen, J. H. Chen, and co‐workers through a simple strategy. Benefitting from well defined structural features including excellent porous carbon structure, N/Co‐doping effect, introduction of NRGO, and good contact between N/Co‐doped PCP and NRGO sheets, the hybrid exhibits excellent tri‐functional catalytic activities for ORR, HER, and OER with long‐term stability in both acid and basic media. [ABSTRACT FROM AUTHOR]

[Display omitted] • Core-shell MnCo 2 O 4 @NiFeRu-LDH on Ni foam was synthesized by hydrothermal method. • MnCo 2 O 4 @NiFeRu-LDH/NF can function as highly effective electrocatalyst toward OER. • The unique 3D nanoarchitecture and synergistic effects result in high performance. • An efficient acid/alkali water electrolyzer was set up using as-prepared anode. • The electrolyzer yields a current density of 100 mAcm−2 with voltage only 0.94 V. The development of high-efficiency oxygen evolution reaction (OER) electrocatalysts is of great importance for electrolytic H 2 generation. In this work, we report in-situ growth of MnCo 2 O 4 nanoneedles and NiFeRu layered double hydroxide (LDH) nanosheets on nickel foam (NF) (MnCo 2 O 4 @NiFeRu-LDH/NF) that can function a highly efficient electrode toward electrocatalysis of OER. Such electrode demands an overpotential of as low as 205 mV to reach 10 mA cm−2 in alkaline electrolyte and can run stably over 120-hours continuous operation. A hybrid flow acid/alkali electrolyzer is set up by using the Pt/C as the acidic cathode coupling with the MnCo 2 O 4 @NiFeRu-LDH/NF as the alkaline anode, which only requires an applied voltage of 0.59 V and 0.94 V to attain an electrolytic current density of 10 mA cm−2 and 100 mA cm−2, respectively. The present work could push forward the further development of the electricity-saving electrolytic technique for H 2 generation. [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]

Ammonia is a vital chemical raw material for both industry and agriculture, the current ammonia synthesis process is based on the Haber-Bosch process yet faces issues of high-energy consumption and high CO 2 emission. Electrochemical nitrite reduction reaction (NO 2 −RR) has been considered as one of the alternative paths for ammonia synthesis. Here, we develop a large-scale viable route for synthesis of 2H–MoS 2 nanosheets (MoS 2 NSs), which show high activity as electrocatalyst for high-efficiency conversion of NO 2 −RR to ammonia, the yields of NH 3 production rate reaches as high as 8.99 mg cm−2 h−1 with a faradaic efficiency of 93.52%. A hybrid electrolytic cell is constructed by coupling MoS 2 NSs as NO 2 −RR cathode in neutral electrolyte with oxygen evolution reaction (OER) in alkaline solution, which can operate stably for more than 120 h with the capability of continuously producing ammonia at the production rate of 38.79 mg cm−2 h−1. • Scalable molten-salt-assisted synthesis MoS 2 nanosheets (MoS 2 NSs). • MoS 2 NSs can effectively electrocatalysis nitrite to NH 3 in neutral media. • The Faradaic efficiency from nitrite to NH 3 catalyzed by MoS 2 NSs reaches 93.52%. • Neutral/alkaline electrolyzer was built for NH 3 production (stability: >120 h). [ABSTRACT FROM AUTHOR]

Highly electrocatalytic activity and strong stability towards both oxygen evolution (OER) and oxygen reduction reaction (ORR) have been regarded as the critical factors in widespread application for the renewable energy technologies. It still remains a huge challenge for developing bifunctional catalysts with low cost, efficiently electrocatalytic activity and strong stability. In this paper, FeCo alloy nanoparticles embedded in nitrogen-doped carbon are synthesized through a simple thermal decomposition of Co-Fe Prussian Blue Analogue (Co-Fe PBA) in Ar atmosphere, during which the organic ligand of CN − in Co-Fe PBA provides both carbon and nitrogen sources for forming nitrogen-doped carbon and FeCo alloy nanoparticles were formed, and thus producing a core-shell structure (FeCo@NC). According to a set of electrochemical tests, the obtained FeCo@NC can function as a Janus to drive OER and ORR with desirable activities and stabilities in alkaline media. Specifically, the FeCo@NC presents an onset-potential of 1.45 V, a potential of 1.49 V at 10 mA cm −2 , a Tafel slope of 62 mV dec −1 as OER catalyst, and an onset potential of 0.94 V, a half-wave potential of 0.8 V as ORR catalyst. The performance is comparable to those of precious metal based electrocatalysts, making it possible for potential application in the renewable energy devices, especially Zn-air battery. [ABSTRACT FROM AUTHOR]

We report a hot-injection method to fabricate monodispersed Cu 3 PdN nanoparticles (NPs). The crystal structure, morphology, and chemical composition of the as-synthesized Cu 3 PdN have been characterized by X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. The as-developed Cu 3 PdN NPs electrocatalysts show improved activity and enhanced stability for formic acid oxidation compared with the corresponding Pd and Cu 3 Pd NPs. [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]

It presents the scalable salt-templated synthesis of two-dimensional porous fluorine-doped carbon (FC) nanosheets with the high active sites and larger special surface area, which shows impressive oxygen reduction reaction (ORR) activities. The synergistic effect of fluoride doping and defects provided more density of active sites in carbon material. It may open up a promising avenue for developing electrocatalysts with high catalytic activity and high stability for electrolyzed application. • Two-dimensional porous fluorine-doped carbon (FC) nanosheets. • Long-term durability and the large active surface area. • Remarkably enhanced oxygen electrocatalytic performance. We present the scalable salt-templated synthesis of two-dimensional porous fluorine-doped carbon (FC) nanosheets. Due to the larger special surface area (1031 m2 g−1) and high active sites, FC-900 (pyrolyzed at 900 °C) shows impressive oxygen reduction reaction (ORR). The synergistic effect of fluoride doping and defects provides richer density of active sites in these nanosheets. When the samples are further calcined at 900 °C for different hours, the ORR activity of the resulting samples shows a little improvement, indicating the influence of the defects on the ORR performance is much inferior to the doped fluorine. The formation of FC structures is beneficial to the ORR activity, and supported by First-principles density functional theory. The results reveal F dopants and defects important role in efficient ORR electrocatalysis owing to the synergistic effect, which is important for comprehending the origin of ORR, and it is also strong evidence to search advanced carbon-based catalysts. [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]

• A family of porous metal-porphyrin triazine-based frameworks (MPTFs) were developed. • NiPTFs-600 exhibited a superb activity of electrocatalytic reduction of CO 2 (ECR-CO 2). • The superb ECR-CO 2 was attributed to abundant N species and Ni-N x active sites. Electrochemical reduction of CO 2 (ECR-CO 2) into high value-added products plays a crucial role in energy conversions. Herein, we developed a family of porous metal-porphyrin triazine-based frameworks (MPTFs-x, M = Mn, Fe, Co, Ni, and Cu, x = temperature) with a specific surface area up to 977 m2 g−1 and homogenously dispersed transition-metals. Benefiting from a high content of N species of 8.43 at.% and abundantly exposed Ni-N x active sites, NiPTFs-600 displayed a superb Faradaic efficiency (FE) of CO production (>90 %) in the range of −0.55 V to −0.95 V with the maximum FE of 97.6 % and current density of 10.8 mA cm-2 at −0.8 V. The reaction mechanism was found to be the adsorption of CO 2 molecules to form *CO 2 intermediates, accompanied by successive protonation to produce *COOH and then *CO. [ABSTRACT FROM AUTHOR]

A novel exfoliated NbS 2 nanosheets produced via liquid exfoliation method exhibited an excellent catalytic activity for nitrogen reduction reaction. • A novel exfoliated NbS 2 nanosheets was produced via liquid exfoliation method. • Exfoliated NbS 2 nanosheets exhibited an excellent catalytic activity for NRR. • The Nb4+ species of exfoliated NbS 2 nanosheets was acted as active sites. • Exfoliated NbS 2 nanosheets was acted as the cathode for a Zn-N 2 battery. • Solar-driven NRR-OER device was achieved with exfoliated NbS 2 nanosheets. Electrochemical nitrogen reduction reaction (NRR) under mild conditions is an attractive prospect for ammonia synthesis. However, this process faces with poor ammonia yield rate and low Faradic efficiency. Herein, we developed exfoliated metallic niobium disulfate (NbS 2) nanosheets for an electrochemical NRR. Owing to more exposed active sites and high electron transfer ability, the exfoliated NbS 2 nanosheets show an extraordinary activity for electrochemical NRR. A high Faradaic efficiency of 10.12 % with an ammonia yield rate of 37.58 μg h−1 mg−1 cat is achieved at −0.5 V versus reversible hydrogen electrode (RHE). The Nb4+ species of exfoliated NbS 2 are confirmed as active sites for NRR. When the exfoliated NbS 2 nanosheets are further assembled into a Zn-N 2 battery and serve as the cathode, an energy density of 714 mA h g−1 with a power density of 0.31 mW cm−2 is achieved. Notably, electrochemical NRR on exfoliated NbS 2 nanosheets can be further driven by solar energy. [ABSTRACT FROM AUTHOR]

Since trivalent arsenite (As III) is considerably more toxic and more difficult to remove from water than pentavalent arsenate (As V), conversion of As III into As V is regarded as an efficient strategy for mitigating arsenic pollution issues. Herein we report a precious-metal-free electrocatalyst with a three-dimensional (3D) structure produced by loading NiCo alloy nanoparticles onto nanocarbon (NiCoNPs/C). A range of techniques were used to characterize the morphology and structure of the NiCoNPs/C electrocatalyst, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Preliminary electrochemical tests demonstrate that the NiCoNPs/C shows a high activity toward electrochemical conversion of arsenite (As III) to arsenate (As V) with quite a high catalytic current at a rather low overpotential. Unlabelled Image • Synthesis of electrocatalyst by loading NiCo alloy nanoparticles on nanocarbon • High activity toward electrochemical conversion of arsenite (As III) to arsenate (As V) • Opens a new avenue for mitigating the risk of arsenic pollution. [ABSTRACT FROM AUTHOR]