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Ammonia (NH3) is an essential resource in human production and living activities, and its demand has been rising in recent years. The catalytic synthesis of NH3 from N2 under mild conditions, inspired by biological nitrogen fixation, has piqued the interest of researchers. In this paper, density functional theory (DFT) calculations were used to investigate the catalytic activity, mechanism, and selectivity of the TM embedded nitrogen-doped phosphorene as high-performance nitrogen reduction reaction (NRR) electrocatalysts in depth. The results show that Nb- and Mo-doped catalysts present excellent catalytic performance, with low limiting potentials of âˆ'0.41 and âˆ'0.18 V, respectively. The Moâ€"N3â€"BP catalyst, for example, not only has an extremely low overpotential (âˆ'0.02 V), but also presents superior selectivity to effectively inhibit the HER competition reaction. A deeper look into the catalytic mechanism reveals a volcano relationship between the d-band center and the catalytic activity (Mo and Nb are located near the peak of the volcano-type curve). The d-band center and charge of the metal center can be regarded as effective descriptors for NRR activity on TM embedded nitrogen-doped phosphorene electrocatalysts, which hope to serve as a guiding principle for the design of high performance NRR single-atom catalyst in the future. [ABSTRACT FROM AUTHOR]

The electrolytic water method is an outstanding hydrogen production process because of its high stability and no restriction. A low-priced and efficient catalyst for electro-deposition of Ni–Co microspheres and nanoclusters on carbon steel (Ni–Co/CS) has been prepared by the dynamic hydrogen bubble template. In the 6 M KOH solution, Ni–Co/CS only requires an overpotential of 48 mV to provide a current density of 50 mA cm−2. At the same time, it also has a large electrochemically active specific surface area (ECSA) and a hydrophilic surface. In addition, the study about the influence of carbon steel (CS) on Ni–Co coatings and the comparison experiment for different base materials has been completed. The results prove that CS is an excellent base material for hydrogen production. It can help the Ni–Co catalyst to have a stable electrolysis in 6 M KOH for 500 h. The above properties of Ni–Co/CS catalyst make it a new choice of hydrogen production by electrolysis of water in practical applications. [ABSTRACT FROM AUTHOR]

The application of electrochemical hydrodechlorination has been impeded due to the low utilization and activity of Pd catalyst. Herein, a series of Pd catalysts were prepared via the controllable evolution of Zn state during the pyrolysis of ZIF-8 nanosheet. Various forms of Pd with different chemical surroundings were generated upon the combined use of galvanic displacement and ion exchange process. Electrocatalytic hydrodechlorination of 4-chlorophenol was performed and the electrocatalytic hydrodechlorination efficiency of Pd/CN reaches 100% within 3 h at extra low Pd concentration. The coexistence of zero-valent Pd (Pd0) and nitrogen coordinated Pd (Pd–N) was verified by XAFS which provide multiple active sites for focusing on adsorbing H* and cracking C–Cl respectively. The synergetic effect between different chemical state of Pd for efficient hydrodechlorination of chloroaromatics and scheme for dexterous preparation of Pd based electrocatalyst are proposed and discussed. [ABSTRACT FROM AUTHOR]

Hollow structure and pore size are considered to be crucial to the performance of nitrogen-doped carbon materials. In this paper, a lipstick-like hollow and mesoporous nitrogen-doped carbon (HNC-1000) material is prepared using a bottom-up template participation strategy. The images by scanning electron microscopy and transmission electron microscopy show that the precursor ZnO particles, the intermediate ZnO@ZIF-8 core–shell particles, and the target HNC-1000 particles all maintain a lipstick-like morphology, and HNC-1000 is a hollow nitrogen-doped carbon material. The specific surface area and pore size analyses show that the synthesized HNC-1000 has a very rich mesoporous structure with Vmeso+macro/Vtotal of 94.8% and mean mesopore size at 13.67 nm. X-ray photoelectron spectroscopy results show that the nitrogen in the catalyst HNC-1000 is mainly pyridine nitrogen and graphite nitrogen. The prepared HNC-1000 has excellent ORR catalytic activity with onset potential (0.98 V versus RHE), half-wave potential (0.85 V versus RHE), and limiting current density (5.51 mA cm−2), which is comparable to that of commercial Pt/C (20 wt%) and superior to NC-1000 derived from pristine ZIF-8. HNC-1000 also has good stability and strong methanol tolerance, which is superior to commercial Pt/C catalyst. The improved performance of HNC-1000 is attributed to its hollow and mesoporous morphology. These findings demonstrate a stratage for the rational design and synthesis of practical electrocatalysts. [ABSTRACT FROM AUTHOR]

Developing new materials that can enhance the efficiency of energy conversion and storage systems is critical to meeting the rising energy demand of low-carbon economies. Mesoporous materials have the advantages of large specific surface area and multiple channels, which can increase efficiency and flexibility in terms of energy and power density. An active catalyst for oxygen reduction reaction (ORR) based on Pt–Cr nanoparticles with ultralow Pt content (0.90 wt%) has been studied in this paper. In contrast, electrocatalyst Pt/Cr/NPC-900 exhibited an ORR activity with onset potential (Eo) of 1.01 V vs. RHE in an alkaline solution that was superior to commercial Pt/C (20 wt%) (0.96 V vs. RHE). The presence of metal oxides and optimal Pt content enhanced the ORR activity. Therefore, the synergistic effect of the high surface area increased charge transfer, and excellent structural stability can achieve significant ORR efficiency, which is conducive to excellent activity. These findings provide a new perspective for economical and practical ORR electrocatalysts to be designed and synthesized rationally. [ABSTRACT FROM AUTHOR]

Co3O4-MoSe2@C nanocomposite has been prepared by a convenient method via combining hydrothermally synthesized MoSe2@C and Co3O4. When catalyzing the hydrogen evolution reaction and oxygen evolution reaction, the catalyst features low overpotentials of 144 mV and 360 mV (both at 10 mA cmâˆ'2 current density), respectively. It can also serve as the cathode in the lithium-oxygen battery and the device shows a low charging-discharging overpotential of 1.50 V with a stable performance of over 200 cycles at current density of 1000 mA gâˆ'1, shedding light on the design and synthesis of novel multifunctional electrocatalysts for energy conversions. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "High-performance bifunctional oxygen electrocatalysts for zinc-air batteries over nitrogen-doped carbon encapsulating CoNi nanoparticles." The authors of the article intend to revise Figure 6 due to limitations in the illustration that may introduce ambiguities and impede interpretation. They have conducted further experiments and data processing to obtain new images that vividly portray the Raman spectrum of the sample, enhancing accuracy for readers. The correct Figure 6 is provided in the document. [Extracted from the article]

The poor electronic conductivity and low intrinsic electrocatalytic activity of metal organic frameworks (MOFs) greatly limit their direct application in electrocatalytic reactions. Herein, we report a conductive two-dimensional Ď€ â€" d conjugated Ni and Co bimetal organic framework (MOF)â€"NiCo-(2,3,6,7,10,11-hexaiminotriphenylene) (NiCo-HITP) nanorods decorated with highly dispersed Co3O4 nanoparticles (NPs) as a promising bi-functional electrocatalyst towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) through an effective and facile strategy by modifying the rod-shaped -Ni3HITP2 crystals using cobalt ions. The triggered electrocatalytic activity of the resulting MOF-based materials was achieved by increasing the electrical conductivity (7.23 S cmâˆ'1) originated from Ni3HITP2 substrate and also by creating the cooperative catalysis sites of Coâ€"N x and Co3O4 NPs. Optimized syntheses show a promising ORR activity with a high half-wave potential (0.77 V) and also a significantly improved OER activity compared with pure Ni3HITP2 in alkaline electrolyte. Furthermore, a rechargeable Znâ€"air battery using the as-prepared material as air-cathode also shows a high power density (143.1 mW cmâˆ'2)â€"even comparable to a commercial Pt/C-RuO2-based battery. This methodology offers a new prospect in the design and synthesis of non-carbonized MOF bi-functional electrocatalysts for efficient catalysis towards ORR and OER. [ABSTRACT FROM AUTHOR]

In this study, we deposited Cu2ZnSnS4 (CZTS) thin films with various thicknesses using electrodeposition and sputtering methods to exploit them as counter electrodes (CEs) in Zn2SnO4 -based dye-sensitized solar cells (DSSCs). The ternary Zn2SnO4 compound with wide bandgap energy, large corrosive resistivity, high electron mobility, and an appropriate conduction band edge position concerning the dye molecules (N719) can be an outstanding alternative for photoanode besides CZTS CE in DSSCs. On the other hand, CZTS is an impressive candidate as a CE material, but its electrocatalytic activity for the recovery of ionic species can be different depending on the synthesis process. Our results indicated the creation of porous morphology in the solution-based deposited films, which yields higher electrocatalytic activity in the CE performance in comparison with the physical deposition method, resulting in short circuit current densities of 9.77 and 8.40 mA cm−2 and open-circuit voltages of 633 and 583 mV for the DSSCs prepared by the respective techniques. The large active area and highly crystallized CZTS films, prepared by the electrodeposition method, led to an around 50% efficiency improvement compared to the widely used, more expensive platinum. [ABSTRACT FROM AUTHOR]

The development of low-cost, highly efficient and stable non-precious metal electrocatalyst for the oxygen reduction reaction (ORR) substituting Pt has attracted much attention. Herein, we developed a promising structural platform for the fabrication of carbon nanospheres functionalized with hollow nanostructures of M-NHCS (M = Fe, Co and Mn) based on metallo-deuteroporphyrins (MDP). Benefited from the multi-layered active sites and hollow substrate with more exposed active surface area, convenient channels for the transport of electrons, the resulting Fe-NHCS electrocatalysts exhibit enhanced electrocatalytic performance in ORR with an onset potential of 0.90 V (versus RHE), and a high selectivity in the direct 4-electron pathway. The Fe-NHCS electrocatalysts also show a good methanol tolerance superior to Pt/C catalysts and an extremely high stability with only 13.0 mV negative after 5000 cycles in alkaline media. Experiments have verified that maintaining the multi-layered Fe−N−C active sites and hollow substrate were essential to deliver the high performance for ORR. The work opens new avenues for utilizing MDP-based materials in future energy conversion applications. [ABSTRACT FROM AUTHOR]

The electrochemical hydrogen evolution reaction (HER) is a promising strategy for production of hydrogen; however, it is still restricted by appropriate efficient and low-cost electrocatalysts. Herein, for the first time, the n-octylammonium hypophosphite, a kind of protic ionic liquid (IL), was used as a new phosphorus source for the manufacture of nickel metaphosphate (Ni2P4O12) electrocatalysts. In contrast to traditional multi-step fabrication processes, the n-octylammonium hypophosphite acted as both reactant and solvent to synthesize Ni2P4O12 by a one-step calcination approach. The obtained Ni2P4O12 as an alkaline HER catalyst required a low overpotential of 116 mV at −10 mA cm−2 and a small Tafel slope of 97 mV dec−1, comparable to the majority of reported Ni-based materials and other phosphate catalysts. Furthermore, this catalyst exhibited robust stability with no distinct attenuation of current density after a long-term durability test in 1 M KOH. Therefore, this task-specific IL strategy with a simple reaction system, reducing the occurrence of side reactions, provided a new perspective on design of high-efficiency metaphosphate electrocatalysts. [ABSTRACT FROM AUTHOR]

Ternary phosphides are attracting great attention in the field of electrocatalytic hydrogen evolution and they have been verified to be highly active for water splitting. Herein, we developed polyaniline (PANI) coated nickel–cobalt metal phosphides nanowire arrays grown on nickel foam (NiCoP@PANI) as hydrogen evolution reaction electrocatalysts. The appearance of PANI with excellent electric conductivity can accelerate H+ in electrolyte transfer into H2 and offer a masking layer to restrain the damage of electrode structural. Besides, the 3D porous structural of nickel foam can act as a skeleton to avoid electrode structure collapse and a channel for electron transfer. The optimized NiCoP@PANI can drive a current density of 10 mA cm−2 at low overpotential of 80.6 mV in 1 M KOH solution, and satisfactory electrochemical stability with unbroken structure and unchanged composition after electrochemical test. [ABSTRACT FROM AUTHOR]

In the present study, an effective approach is proposed to replace the oxygen evolution reaction with the substituted anodic hydrazine oxidation reaction (HzOR) to assist in hydrogen generation based on a bifunctional porous Ni-Zn electrocatalyst with nanosheet arrays. The Ni-Zn catalyst exhibits an extraordinary HzOR performance with a high current density of 970 mA cm−2 at 0.7 V, and 93.8% of its initial activity after 5000 s, simultaneously delivering an overpotential of 68 mV at 10 mA cm−2 for the hydrogen evolution reaction. Moreover, the electrolytic cell is constructed employing Ni-Zn catalysts as both the anode and cathode, achieving 100 mA cm−2 at an ultralow cell voltage of 0.497 V with an outstanding stability over 10 h. The superior electrocatalytic performance can be ascribed to its porous structure with large active surface area, high electrical conductivity, and most importantly the super-aerophobic nature of the Ni-Zn surface. This work also provides a novel approach to designing and constructing porous structured non-noble metal bifunctional electrocatalysts with super-aerophobic surface to be used for energy-saving hydrogen production. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER), a sluggish multistep process in electrochemical water splitting, is still a challenging issue to achieve with cheap, earth-abundant non-precious and non-polluting materials. In this work, three different electrocatalysts, specifically NiCo2O4, NiCo2 S4, and NiCo2 Se4, synthesized by simple hydrothermal process, show excellent OER activity. This report not only projects OER performances but also demonstrates a modified method for the transformation of NiCo2O4 to NiCo2 S4 and NiCo2 Se4 via sulfidation and selenization reactions. The well crystalline, porous nature of NiCo2O4, NiCo2 S4, and NiCo2Se4 electrocatalysts with one dimensional (1D) structural morphology affords overpotentials of 346 mV, 309 mV and 270 mV at current density of 10 mA cm–2 in 1 M KOH. In particular, NiCo2Se4 exhibits a low overpotential as well as a smaller Tafel slope of 63 mV dec−1, leading to robust stability in alkaline conditions. The abundant active sites, large mass and size of NiCo2Se4 enhances the performance of the OER. This type of selenide-based material with low toxicity is also an advantage for eco-friendly applications. [ABSTRACT FROM AUTHOR]

The design of highly active, Earth-abundant and stable electrocatalysts is important for efficient water splitting. In this work, we report the fabrication of RuP and Ru2P nanoparticles supported on ordered macroporous N-doped carbon hollow spheres (RuP/H-NC and Ru2P/H-NC) through a facile and scalable space-confined pyrolysis process. The RuP/H-NC catalyst exhibits Pt-like activity in alkaline electrolyte, by means of the macroporous structure with a larger specific area and more exposed active sites, as well as the synergistic effect between the RuP nanoparticles and N-doped carbon. Specifically, the RuP/H-NC catalyst yields superior hydrogen evolution reaction activity in terms of low overpotential of 19 mV in 1 M KOH to achieve a current density of 10 mA cm−2 and excellent durability, outperforming Ru2P/H-NC and most of the reported non-Pt catalysts. Further density function theory calculation reveals that RuP is more intrinsically active with favorable hydrogen adsorption Gibbs free energy than that of Ru2P. [ABSTRACT FROM AUTHOR]

Understanding the interfacial properties of catalyst/substrate is crucial for the design of high-performance catalyst for important chemical reactions. Recent years have witnessed a surge of research in utilizing MoS2 as a promising electro-catalyst for hydrogen production, and field effect has been employed to enhance the activity (Wang et al 2017 Adv. Mater. 29, 1604464; Yan et al 2017 Nano Lett. 17, 4109–15). However, the underlying atomic mechanism remains unclear. In this paper, by using the prototype MoS2/Au system as a probe, we investigate effects of external electric field on the interfacial electronic structures via density functional theory (DFT) based first-principles calculations. Our results reveal that although there is no covalent interaction between MoS2 overlayer and Au substrate, an applied electric field efficiently adjusts the charge transfer between MoS2 and Au, leading to tunable Schottky barrier type (n-type to p-type) and decrease of barrier height to facilitate charge injection. Furthermore, we predict that the adsorption energy of atomic hydrogen on MoS2/Au to be readily controlled by electric field to a broad range within a modest magnitude of field, which may benefit the performance enhancement of hydrogen evolution reaction. Our DFT results provide valuable insight into the experimental observations and pave the way for future understanding and control of catalysts in practice, such as those with vacancies, defects, edge states or synthesized nanostructures. [ABSTRACT FROM AUTHOR]

A simple and novel approach for the preparation of a Pt/reduced graphene oxide nanoscroll (Pt/RGOS) nanocatalyst is reported for the first time. The Pt/reduced graphene oxide (Pt/RGO) was fabricated by the co-reduction of GO and Pt salt using ethylene glycol under microwave irradiation, then the Pt/RGOSs were obtained by oxygen implosion in situ rolling up of the Pt/RGO using catalytic decomposition of Pt towards H2O2 under ultrasonication. Transmission electron microscopy shows that the Pt nanoparticles are uniformly dispersed on the reduced graphene oxide nanoscrolls with tubular structure, open edges and ends, and tubular diameter ranging from 10 to 100 nm. X-ray diffraction indicates that the crystal structure and diffraction intensity of the platinum practically remains unchanged, and the RGO has not been oxidized before or after rolling. Raman spectroscopy reveals that the Pt/RGOSs have a higher D=G ratio (1.2) than Pt/RGO (1.1). BET (Brunauer, Emmett and Teller) results exhibit that the Pt/RGOSs possess higher specific surface area and broader pore size range (188 m2 g-1, 25-45 nm) than Pt/RGO (122 m2 g-1, 30-38 nm). Additionally, the electrocatalytic performance of the Pt/RGOSs for methanol oxidation was evaluated, and the results show that the Pt/RGOSs possess significantly higher electrocatalytic activity and stability than Pt/RGO. [ABSTRACT FROM AUTHOR]

It is very important to develop enhanced electrochemical sensing platforms for molecular detection and non-noble-metal nanoarray architecture, as electrochemical catalyst electrodes have attracted great attention due to their large specific surface area and easy accessibility to target molecules. In this paper, we demonstrate that an Fe2Ni2N nanosheet array grown on Ti mesh (Fe2Ni2N NS/TM) shows high electrocatalytic activity toward glucose electrooxidation in alkaline medium. As an electrochemical glucose sensor, such an Fe2Ni2N NS/TM catalyst electrode demonstrates superior sensing performance with a short response time of less than 5 s, a wide linear range of 0.05 μM–1.5 mM, a low detection limit of 0.038 μM (S/N = 3), a high sensitivity of 6250 μA mM−1 cm−2, as well as high selectivity and long-term stability. [ABSTRACT FROM AUTHOR]

A novel three-dimensional (3D) bifunctional electrocatalyst, CoNi alloy nanoparticle and carbon nanotube decorated N-doped carbon nanosheet arrays on carbon cloth (CoNi alloy/NCNSAs/CC) derived from polymetallic organic frameworks, is firstly prepared. The CoNi alloy/NCNSAs/CC-800 fabricated by pyrolyzing at 800 °C exhibits an oxygen reduction reaction (ORR, limiting current density) of 6.5 mA cm−2 and a superior oxygen evolution reaction (OER, at 10 mA cm−2) of 1.51 V, as well as a smaller potential difference of 0.676 V between OER and ORR half-wave potential, outperforming previous self-supporting cathodes. Flexible Zn-air batteries (FZABs) assembled with the CoNi alloy/NCNSAs/CC-800 exhibit higher energy density (98.8 mW cm−2) and higher capacity (879 mAh g−1), as well as excellent mechanical cycle ability (lower voltage gap of 0.66 V during the charge/discharge cycles at flat and folded state), significantly outstripping all other FZABs with self-supporting electrodes currently reported. Such a remarkable performance is ascribed to the 3D hierarchical nanostructure which promotes mass transport, the higher graphitization facilitating electronic mobility and the evenly dispersed active sites which accelerate kinetic reactions. So CoNi alloy/NCNSAs/CC-800 is a promising cathode candidate for ideal wearable energy devices and has great potential application in the field of electrochemical energy storage and conversion. [ABSTRACT FROM AUTHOR]

High-efficiency and low-cost electrocatalysts are generally believed to be the critical factor and have been highly researched to catalyze the oxygen reduction reaction (ORR) during the operation of Li–O2 battery (LOB). The catalysts with better ORR performance are essential for high-performance LOBs. Herein, a binder-free MnOx@carbon cloth cathode composed of Mn3O4 nanoparticles and Mn2O3 nanosheets were directly synthesized on the carbon cloth by electrodeposition and subsequently heat treatment at different temperature (from 200 °C to 400 °C). With the increase of temperature, the Mn3O4 nanospheres gradually transformed into Mn2O3 nanosheets. The MnOx obtained at 350 °C exhibited the best ORR performance. And MnOx-350 °C could operate more than 80 cycles at 340 mA g−1 with a limiting specific capacity of 1000 mAh g−1, and its first discharge specific capacity could nearly achieve 8000 mAh g−1 at 200 mA g−1. [ABSTRACT FROM AUTHOR]

Transition metal chalcogenides have attracted much attention as high-performance electrocatalysts for hydrogen evolution reaction (HER). Here, we synthesized an efficient HER electrocatalyst of amorphous ruthenium sulfide (A-RuS2), exhibiting an overpotential of 141 mV at the current density of 10 mA cm−2 and a Tafel slope of 65.6 mV dec−1. Experiments demonstrate amorphous RuS2 has much better catalytic activity than that of its crystalline counterparts. Our study shows that amorphous RuS2 has increased intrinsic activity and active sites. This work provides a feasible strategy for the development of HER electrocatalysts in amorphous state. [ABSTRACT FROM AUTHOR]

Herein, we design a dual-template-assisted pyrolysis method to prepare ultra-small Fe3O4 nanoparticles anchored on Fe/N-doped hollow porous carbon spheres (0.010-Fe/NHPCS-800) for oxygen reduction reaction (ORR). The synthesized SiO2 nanospheres, which are selected as the hard template, contribute to forming macroporous structure. Pluronic ® F127 is employed to fabricate mesopores through high-temperature pyrolysis as a soft template. In this way, the 0.010-Fe/NHPCS-800 architecture represents an ordered hierarchically porous property with a large BET surface area (1812 m2 g−1), which can facilitate the mass transport of reactants and increase the electrochemically active area. The Fe3O4 nanoparticles wrapped by graphitic carbon layers provide more active sites, and the synergistic interaction between Fe3O4 nanoparticles and doping N has a positive effect on ORR performance. The 0.010-Fe/NHPCS-800 catalyst outperforms the most effective ORR activities among a series of Fe/NHPCS samples with onset potential of 0.95 V (versus reversible hydrogen potential) and half-wave potential of 0.81 V, which is almost the same as the commercial Pt/C (0.96 and 0.81 V, correspondingly) in 0.10 M KOH. However, both the stability and durability of 0.010-Fe/NHPCS-800 surpass those of commercial Pt/C. Given all these advantages, 0.010-Fe/NHPCS-800 is a promising candidate to take the place of Pt-based electrocatalysts for ORR in the future. [ABSTRACT FROM AUTHOR]

Exploring efficient metal-free electrocatalysts for oxygen reduction reactions (ORR) will have a great impact on the field of fuel cells and metal-air batteries. In this paper, we report a simple and efficient routine to coat ordered mesoporous carbon (CMK-3) with nitrogen-doped carbon via pyrolysis of the surface-self-polymerized polydopamine. The optimized CMK-3 catalyst with a coating of nitrogen-doped carbon demonstrates excellent electrocatalytic activity towards ORR in alkaline media. The coating procedure under optimized conditions lowers the ORR half-wave-potential by 80 mV, giving a genuine metal-free catalyst with an onset ORR potential of 0.96 V (vs reversible hydrogen electrode (RHE)) and half-wave potential of 0.83 V (vs RHE) in 0.1 M KOH, which is much better than other carbon material-based catalysts (such as carbon nanotubes and their composites). The performance of this surface-nitrogen-rich CMK-3 catalyst is also superior to that of N-doped ordered mesoporous carbon synthesized by means of the ‘nanocasting’ technique. Furthermore, the as-prepared catalyst performs comparably in terms of activity, superior durability, and higher tolerance to methanol compared with commercially available Pt/C. [ABSTRACT FROM AUTHOR]

Many efforts have been devoted to the exploration of non-noble-metal electrocatalysts for the hydrogen evolution reaction (HER) in recent years. Here, we have developed a 3D-MoO2 microsphere supported MoSe2 for HER, via a facile hydrothermal approach followed by selenylation treatment. Loosely stacked MoSe2 layers are formed on the conductive MoO2 surface, and act as active sites for HER. Meanwhile, the metallic inner MoO2 facilitates electron transport for proton reduction. In addition, the MoSe2 could protect the inner MoO2 from the acidic electrolyte in the HER precess. Significantly, the as-synthesized MoO2/MoSe2 exhibits excellent catalytic activity for HER, characterised by a low onset potential of −101 mV vs reversible hydrogen electrode, a small overpotential of 167 mV at a current density of 10 mA cm−2, along with Tafel slope values of 68 mV dec−1, as well as outstanding stability in 0.5 mol L−1 H2SO4. [ABSTRACT FROM AUTHOR]

It is highly challenging to explore high–performance bi-functional oxygen electrode catalysts for their practical application in next-generation energy storage and conversion devices. In this work, we synthesize hierarchical N–doped carbon microspheres with porous yolk–shell structure (NCYS) as a metal-free electrocatalyst toward efficient oxygen reduction through a template-free route. The enhanced oxygen reduction performances in both alkaline and acid media profit well from the porous yolk–shell structure as well as abundant nitrogen functional groups. Furthermore, such yolk–shell microspheres can be used as precursor materials to motivate the oxygen reduction activity of oxygen evolution oriented materials to obtain a desirable bi-functional electrocatalyst. To verify its practical utility, Zn–air battery tests are conducted and exhibit satisfactory performance, indicating that this constructed concept for preparation of bi-functional catalyst will afford a promising strategy for exploring novel metal–air battery electrocatalysts. [ABSTRACT FROM AUTHOR]

Large over-potentials during battery operation remain a big obstacle for aprotic Li–O2 batteries. Herein, a nanocomposite of about 4 nm cobalt monoxide nanocrystals grown in situ on reduced graphene oxide substrates (CoO/RGO) has been synthesized via a thermal decomposition method. The CoO/RGO cathode delivers a high initial capacity of 14 450 mAh g−1 at a current density of 200 mA g−1. Simultaneously it displays little capacity fading after 32 cycles with a capacity restriction of 1000 mAh g−1. Additionally, compared with Ketjenblack and general CoO nanoparticles, ultrathin CoO nanoparticle-decorated RGO electrode materials with a delaminated structure display an observable reduction of over-potential in Li–O2 batteries. These results demonstrate that the introduction of RGO improves the performance of CoO, which is a promising strategy for optimizing the design of electrocatalysts for aprotic rechargeable Li–O2 batteries. [ABSTRACT FROM AUTHOR]

The design and fabrication of a methanol-tolerant electrocatalyst is still one of the most important issues in direct methanol fuel cells (DMFCs). Here, we focus on the design of a cathodic electrocatalyst in DMFCs and describe a new methanol-tolerant electrocatalyst fabricated from poly(vinylpyrrolidone) (PVP) coating on platinum nanoparticles assisted by hydrogen bonding between PVP and polybenzimidazole (PBI). The PVP layer has a negligible effect on the oxygen reduction reaction (ORR) activity, while the methanol oxidation reaction is retarded by the PVP layer. The PVP-coated electrocatalyst shows higher ORR activity under various methanol concentrations in the electrolyte, suggesting that the PVP-coated electrocatalyst has a higher methanol tolerance. Also, the PVP-coated electrocatalyst loses only 14% of the electrochemical surface area after 5000 potential cycles from 0.6–1.0 V versus the reversible hydrogen electrode, indicating better Pt stability than non-coated (27%) and commercial (38%) electrocatalysts due to the unique sandwich structure formed by the PVP and PBI. The power density of the PVP-coated electrocatalyst is four to five times higher compared to non-coated and commercial electrocatalysts with 12 M methanol feeding to the anode side, respectively. PVP coating is important for the enhancement of Pt stability and methanol tolerance. This study offers a new method for preparing a low-cost and high-methanol-tolerant Pt electrocatalyst, and useful information for real DMFC application to eliminate the methanol crossover problem in the cathode side. [ABSTRACT FROM AUTHOR]

In order to combine the advantages of both 0D and 1D nanostructured materials into a single catalyst, density functional theory (DFT) calculations have been used to study the PdCu alloy NP-decorated Cu nanotubes (PdCu@CuNTs). These present a significant improvement of the electrocatalytic activity of formic acid oxidation (FAO). Motivated by our theoretical work, we adopted the seed-mediated growth method to successfully synthesize the nanostructured PdCu@CuNTs. The new catalysts triple the catalytic activity for FAO, compared with commercial Pd/C. In summary, our work provides a new strategy for the DFT prediction and experimental synthesis of novel metal NP-decorated 1D nanostructures as electrocatalysts for fuel cells. [ABSTRACT FROM AUTHOR]

In this letter, we report on the use of a cobalt phosphide nanowall array on conductive carbon cloth (CoP NA/CC) as an efficient catalyst electrode for methanol electro-oxidation under alkaline conditions. This CoP NA/CC achieves a current density of 96 mA cm–2 toward 0.5 M methanol at 0.5 V (versus a saturated calomel electrode (SCE)) in 1 M KOH. Moreover, this electrode exhibits superior stability and 93% of the initial anodic current density can be retained after 1000 cyclic voltammetry cycles when re-measured in new electrolyte. [ABSTRACT FROM AUTHOR]

A facile, self-foaming strategy is reported to synthesize porous, nitrogen-doped carbon nanosheets (N-CNSs) as a metal-free electrocatalyst for oxygen reduction reaction (ORR). Benefiting from the synergistic functions of N-induced active sites, a highly specific surface area and continuous structure, the optimal N-CNS catalyst exhibits Pt-like ORR activity (positive onset potential of ∼0 V versus Ag/AgCl and limiting current density of 5 mA cm−2) through a four-electron transfer process in alkaline media with excellent cycle stability and methanol tolerance. This work not only provides a promising metal-free ORR catalyst but also opens up a new path for designing carbon-based materials towards broad applications. [ABSTRACT FROM AUTHOR]

In this letter, we demonstrate for the first time that cobalt phosphide nanowires (CoP NWs) exhibit remarkable catalytic activity toward electrochemical detection of hydrogen peroxide (H2O2). As an enzymeless H2O2 sensor, such CoP NWs show a fast amperometric response within 5 s and a low detection limit of 0.48 μM. In addition, this nonenzymatic sensor displays good selectivity, long-term stability and excellent reproducibility. [ABSTRACT FROM AUTHOR]

As a green and highly efficient energy resource, hydrogen (H2) has attracted much attention in recent years. Electrochemical water splitting is an economic process to generate H2. MoS2 is a promising candidate to replace traditional Pt-based electrocatalysts for the hydrogen evolution reaction (HER) under acidic conditions. But low electrical conductivity is one of bottlenecks for the large-scale application of MoS2. In this work, a carbon-coated MoS2 hybrid electrocatalyst was prepared with a chemical vapour deposition (CVD) approach to improve the electrical conductivity of MoS2. In addition to the surface-coating carbon, a small graphene-like layer could also be inserted into the interlayers of MoS2 during the CVD process which resulted in more active sites being exposed in MoS2. Enhanced electrical conductivity and more exposed active sites lead to excellent HER activity. [ABSTRACT FROM AUTHOR]

We report a solvothermal method preparation of dendritic Pd nanoparticles (DPNs) and spherical Pd nanoparticles (SPNs) supported on reduced graphene oxide (RGO). Drastically different morphologies of Pd NPs with nanodendritic structures or spherical structures were observed on graphene by controlling the reduction degree of graphene oxide (GO) under mild conditions. In addition to being a commonplace substrate, GO plays a more important role that relies on its surface groups, which serves as a shape-directing agent to direct the dendritic growth. As a result, the obtained DPNs/RGO catalyst exhibits a significantly enhanced electro-catalytic behavior for the oxidation of formic acid compared to the SPNs/RGO catalyst. [ABSTRACT FROM AUTHOR]