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Here, we report a highly efficient ORR electrocatalyst with Fe–N4 active sites uniformly dispersed on a three-dimensional (3D) interconnected porous nitrogen-doped carbon network synthesized by pyrolyzing SiO2@ZIF-8 composites loaded with iron salts. The as-prepared single-atom Fe 3D-ordered mesoporous carbon (SA-Fe-3DOMC) possesses a high specific surface area of 1357.8 m2 g−1 and a high Fe loading of 0.84 wt% as well. Benefiting from these favourable structural properties, SA-Fe-3DOMC exhibits a superior ORR half-wave potential (E1/2) of 0.901 V and negligible activity loss (only 3 mV) after 10 000 cycles in alkaline media, surpassing the state-of-the-art Pt/C electrocatalyst. Particularly, an integrated zinc–air battery with SA-Fe-3DOMC as the air electrode shows a remarkable peak power density (140 mW cm−2) and a high specific capacity (786.6 mA h g−1), demonstrating great potential for practical application. [ABSTRACT FROM AUTHOR]

As the demand for green hydrogen (H2) rapidly increases, the development of water electrolysis technology has been receiving great attention. Indeed, recent remarkable advances in catalyst materials increased the feasibility of water electrolysis for a future H2 economy and technology. In this review, we summarize representative non-precious group metal-based materials for achieving active and stable water electrolysis performances. Our comprehensive range of the state-of-the-art catalysts includes doped carbon catalysts, metal borides, metal carbides, metal oxides, metal phosphides, metal sulfides, and single-atom catalysts. For each class of materials, we focus on the synthesis and catalytic performances of the state-of-the-art materials toward water electrolysis and present the current challenges and outlooks of such materials, along with prospective insights to develop and realize practical systems. [ABSTRACT FROM AUTHOR]

Densely vertical-grown NiFe hydroxide nanosheets on a nickel foam (DVS-NFOH@NF) were designed and synthesized for a dendrite-free lithium anode. As a result, the Li dendrite was significantly suppressed. The invented Li anode presented a uniform morphology and great cycle performance in a symmetric cell. [ABSTRACT FROM AUTHOR]

Herein, carbonized nickel metal organic framework scaffolds at nickel foam (CNS@NF) were fabricated to regulate Li-ion plating/stripping in lithium cells. CNS@NF would contribute to uniform Li nucleation and low overpotential due to the small lattice mismatch ratio and homogenous lithiophilic sites. Moreover, the spongy structure of the carbonized MOF can reduce the local current density by smoothening the sharp edges of NiO. Owing to these advantages, both the symmetric cells and full cells exhibited excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

A "superaerophobic" NiCo bimetallic phosphide electrocatalyst has been fabricated by employing bimetal–organic frameworks as self-sacrificing templates. An overpotential of only 205 mV can drive the HER current density to 800 mA cm−2, which is even superior to that for Pt/C. This study provides a promising approach for the development of industrialized HER electrocatalysts. [ABSTRACT FROM AUTHOR]

NH3 synthesis via the electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions has been regarded as a sustainable strategy for fertilizer production and hydrogen fuel storage and mitigating greenhouse gas emissions. The faradaic efficiency (FE) and reaction rate of the NRR, however, are still low for current electrocatalysts. Herein, we develop a metal-free B, N co-doped porous carbon nanofiber (B/N–CNF) that exhibits superior electrocatalytic performance for the NRR in an alkaline electrolyte with the highest FE of 13.2% at −0.5 V and a NH3 yield rate of 32.5 μg h−1 mgcat.−1 at −0.7 V. Such a high NRR activity of the B/N–CNF is superior to that of N- or B-doped carbon materials in the literature. The experimental results reveal that the B–N bonds play a critical role in the NRR process, in which N atoms promote the electron conductivity and B atoms efficiently enhance the N2 adsorption and charge transfer. [ABSTRACT FROM AUTHOR]

Achieving a high faradaic efficiency and mass activity simultaneously on catalysts is critical in accelerating the practical application of CO2 electrochemical reduction. In this study, Au–Pd core–shell nanoparticles consisting of an ultrathin Pd-rich shell and an Au–Pd alloy core are developed by a simple one-pot synthesis method and evaluated for CO2-to-CO conversion. By adjusting the Au : Pd feeding ratio, the shell thickness and composition in the nanoparticle can be tuned. Significantly improved CO selectivity as compared to pure Au and Pd counterparts can be obtained on all the synthesized Au–Pd core–shell nanoparticles with a maximum faradaic efficiency of 96.7% at −0.6 V. The Au94Pd6 catalyst shows an ultrahigh mass activity of 99.8 A gPd+Au−1 for CO production at an overpotential of merely 390 mV. Combined in situ infrared absorption spectroscopy and density functional theory studies reveal that the easier desorption of *CO due to the more balanced *COOH/*CO adsorption energies on Au–Pd core–shell surfaces is responsible for the improved catalytic performance. [ABSTRACT FROM AUTHOR]

Non-noble metal electrocatalysts toward the oxygen reduction reaction (ORR) are highly required to substitute expensive Pt/C as the cathode of proton exchange membrane fuel cells. However, the relatively low ORR activity of Pt-free catalysts under acidic conditions is the major issue. Herein, we engineered a three-dimensional structure consisting of atomically dispersed Fe, N-doped hollow carbon nanospheres linked by carbon nanotubes as an electrocatalyst for the ORR. Benefiting from the unique structure and high-density atomic Fe–Nx sites, this new type of electrocatalyst showed an impressive ORR half-wave potential of 0.84 V and kinetic current density of 13.1 mA cm−2 at a potential of 0.8 V in acidic media, which was even better those of commercial Pt/C. [ABSTRACT FROM AUTHOR]

The rational construction of carbon materials with well-designed porosity and appropriate surface functionality is of critical significance for high-performance supercapacitors. Herein, we report a design strategy for the facile synthesis of N/S-co-doped carbon nanobowls through a one-pot condensation and carbonization process. The carbon nanostructure can be changed from a nanoball to a nanobowl by elaborately controlling the capillary compression and nanoshell thickness. The N/S-co-doped carbon nanobowls greatly increase the volumetric density by eliminating hollow interiors. The unique hierarchical micro/mesoporosity and the N,S-functionalized structure enable the carbon nanobowls to utilize the high specific surface area efficiently resulting in high specific capacitance and ultrafast charge/discharge capability. The electrochemical benefits endow the symmetric supercapacitors with a high energy density of 9.6 W h kg−1, a maximum power density of 475.5 kW kg−1, and a long cycle lifetime over 50 000 cycles. These encouraging results demonstrate the potential of the N/S-co-doped carbon nanobowls for application in ultrahigh-power supercapacitors. [ABSTRACT FROM AUTHOR]

The fundamental understanding of the impacts induced by anions on oxygen reduction reaction (ORR) in alkaline media is of great importance in the design of more advanced catalysts for alkaline fuel cells (AFC). In this study, the specific adsorption of F−, Cl−, ClO4−, CO32−, SO42−, and citrate anions on Pt/C and Pd/C catalysts, and their impacts on the ORR kinetics in alkaline solutions were systematically studied. It was found that F−, Cl− and ClO4− did not specifically adsorb on Pt or Pd surfaces and had no poisoning effect on ORR. CO32− and SO42− had significant effects on Pt/C and lowered the activity even at a very low concentration. On the other hand, their impacts on Pd/C were negligible. Self-dissociation of citrate anions was found to occur on both Pt/C and Pd/C in the H adsorption/desorption and double layer regions. For the first time, surface enhanced infrared absorption spectroscopy (SEIRAS) with the attenuated total reflection (ATR) technique was used to investigate the self-dissociation of citrate on Pt and Pd thin film electrodes. The breaking of carboxylic groups and the carbon backbone was proposed as a possible dissociation pathway for citrate. The adsorbed species have a negligible effect on ORR activity on Pt/C as they are removed by oxidation before 0.75 V. In contrast, their oxidation on Pd/C surfaces is not completed until 0.91 V, which causes a lower ORR activity observed in rotating disk electrode measurements. The findings in this paper emphasize the importance of specific adsorption of anions and double-layer interfacial effects on the ORR activity measurement in alkaline solutions. [ABSTRACT FROM AUTHOR]

Exotic AuPd bimetallic nanoflowers (NFs) are facilely synthesized using a microorganism-mediated, cetyltrimethylammonium chloride (CTAC)-directed method at room temperature. The NFs consist of one-dimensional long pedicels and three-dimensional open horns. The effect of cell dosage and feed concentrations of ascorbic acid (AA), CTAC and metal precursors on the morphology of the bimetallic nanostructures were studied. The results showed that all the obtained materials were alloys with Pd-enriched surfaces. The diameters of the horns decreased, while those of the pedicels increased with increasing the feed concentration of Pd precursor. The presence of Pd precursor was vital for the formation of the nanowire part of the NF structure. Furthermore, the AuPd-NF/microorganism materials exhibited excellent catalytic performance and durability toward the hydrogenation of 1,3-butadiene. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction (ORR) activity as a function of thickness of the Pt shell on Pt-Ni alloy nanoparticles was established. We demonstrated that the effects of transition metals could only extend to a very thin Pt shell, which was 0.9-1.0 nm for Pt3Ni. [ABSTRACT FROM AUTHOR]

A comprehensive experimental study was conducted on the dealloying of PdNi6 nanoparticles under various conditions. A two-stage dealloying protocol was developed to leach ＞95% of Ni while minimizing the dissolution of Pd. The final structure of the dealloyed particle was strongly dependent on the acid used and temperature. When H2SO4 and HNO3 solutions were used in the first stage of dealloying, solid and porous particles were generated, respectively. The porous particles have a 3-fold higher electrochemical surface area per Pd mass than the solid ones. The dealloyed PdNi6 nanoparticles were then used as a core material for the synthesis of core–shell catalysts. These catalysts were synthesized in gram-size batches and involved Pt displacement of an underpotentially deposited (UPD) Cu monolayer. The resulting materials were characterized by scanning transmission electron microscopy (STEM) and in situ X-ray diffraction (XRD). The oxygen reduction reaction (ORR) activity of the core–shell catalysts is 7-fold higher than the state-of-the-art Pt/C. The high activity was confirmed by a more than 40 mV improvement in fuel cell performance with a Pt loading of 0.1 mg cm−2 by using the core–shell catalysts. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction (ORR) activities of Pt shells were found to have a strong dependence on the surface structure by depositing them on Pd nanocrystals with different shapes. [ABSTRACT FROM AUTHOR]

Lithium-sulfur batteries (LSBs) with two typical platforms during discharge are prone to the formation of soluble lithium polysulfides (LiPS), leading to a decrease in the cycling life of the battery. Under practical working conditions, the transformation of S 8 into Li 2 S is cross-executed rather than a stepwise reaction, where the liquid LiPS to solid Li 2 S conversion can occur at a high state of charge (SOC) to maintain the current requirement. Therefore, advancing Li 2 S deposition can effectively reduce the accumulation of LiPSs and ultimately improve the reaction kinetics. Herein, a "butterfly material" GeS 2 -MoS 2 /rGO is used as a sulfur host. Rich catalytic heterointerfaces can be obtained via the abundant S-S bonds formed between GeS 2 and MoS 2 . MoS 2 (left wing) can enhance LiPS adsorption, while the lattice-matching nature of Fdd 2 GeS 2 (right wing) and Fm 3̄ m Li 2 S can induce multiple nucleation and regulate the 3D growth of Li 2 S. Li 2 S deposition can be advanced to occur at 80% SOC, thereby effectively inhibiting the accumulation of soluble LiPSs. Attributed to the synergistic effect of catalytic and lattice-matching properties, robust coin and pouch LSBs can be achieved., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (This journal is © The Royal Society of Chemistry.)

We have synthesized sub-10 nm Pd cubic and octahedral nanocrystals and then evaluated their activities towards oxygen reduction reaction (ORR). The ORR activity of Pd nanocubes was one order of magnitude higher than that of Pd octahedra, and comparable to that of the state-of-the-art Pt catalysts., (This journal is © The Royal Society of Chemistry 2011)