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The fabrication of flexible catalytic films with isolated single/dual‐atomic sites and their integration in wearable electronics is challenging. Herein, an efficient method to prepare atomically dispersed binary Ni/Co‐decorated flexible carbon nanofiber (NiCo‐CNF) film using formamide‐derived cyano‐specific NiCo‐NC as nanofillers was developed. The optimized Ni1Co1‐CNF catalytic film, having large‐area, high density of adjacent Ni‐N4 and Co‐N4 active sites, and good mechanical properties under repeated bending and release conditions, possessed high catalytic activity towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The ORR/OER potential difference (ΔE10) for Ni1Co1‐CNF at 10.0 mA cm−2 was highly comparable with the Pt/C+RuO2 mixture. In addition, flexible Ni1Co1‐CNF‐assembled Zn‐air battery displayed very good mechanical robustness and cycling stability. Our work may inspire the fabrication of other atomic metal‐decorated films for membrane electrocatalysis. [ABSTRACT FROM AUTHOR]

Density functional theory calculations were employed to investigate the electrochemical oxygen reduction reaction on the (111) and (100) surfaces of cobalt(II) oxide. Different mechanisms were applied to evaluate the oxygen reduction reaction performance of cobalt(II) oxide structures in terms of the Gibbs free energy and density of states. A variety of intermediate structures based on associative and dissociative mechanisms were constructed and optimized. As a result, we estimated the catalytic activity by calculating the free energy of the intermediates and constructing free energy diagrams, which suggested that the oxygen reduction reaction Gibbs free energy on cobalt(II) oxide (111) and (100) surfaces based on the associative mechanism is smaller than that based on the dissociative mechanism, demonstrating that the associative mechanism should be more likely to be the oxygen reduction reaction pathway. Moreover, the theoretical oxygen reduction reaction activity on the cobalt(II) oxide (111) surface was found to be higher than that on the cobalt(II) oxide (100) surface. These results shed light on the rational design of high-performance cobalt(II) oxide oxygen reduction reaction catalysts. [ABSTRACT FROM AUTHOR]

The dechlorination of unconventional carbon source: polyvinyl dichloride (PVDC) by ZnO at the presence of melamine was used to prepare hierarchically Porous N-doped nanoCarbon (PDC). ZnO played the multirole of dechlorination agent, mesopore templates, and most importantly, ZnCl 2 generation source. ZnCl 2 , at latter high temperature treatment, could promote carbonization and lead to hierarchical micro- and mesopore formation, which facilitated mass transportation for electrocatalytic oxygen reduction reaction (ORR). The 900 °C-annealed PDC exhibited ultrahigh activity which comprehensively surpassed the commercially available 20 wt% Pt/C. [ABSTRACT FROM AUTHOR]

Highlights: [•] Very small CoOx particles were incorporated into Ag/rGO composite. [•] CoOx could promote the ORR activity of the resulted nanocomposites. [•] Underlying mechanism was given to explain the high-performance of CoOx-Ag/rGO. [•] Our strategy provides the possiblity to form better Ag-based ORR catalysts. [ABSTRACT FROM AUTHOR]

Solid-phase templates are commonly used for building hollow-structured carbon materials (CMs) but often demand post treatments to remove templates. Herein, we develop an efficient and general method to construct hollow carbonaceous structure via the templating of sacrificial carbon nitride (termed as f-NC) without post treatment. The f-NC template can be decomposed under high-temperature annealing, additionally, it can serve as N source to enrich the N content. Applying f-NC template, we manage the synthesis of hollow-structured highly dispersed binary FeCo-nitrogen-carbon material (termed as f-NC@FeCo-NC). Its hollow feature is confirmed by direct observation using HRTEM. Meanwhile, Fe/Co in oxidation states have been verified uniformly distributing in heavily N-doped CMs (N content ∼ 13.2 at.%). The resulted f-NC@FeCo-NC, as examined by electrochemical measurements, exhibits highly efficient performance toward oxygen reduction reaction (ORR) in alkaline medium. It respectively shows much enhanced onset and half-wave potentials of 1.01 and 0.89 V relative to the FeCo-NC that is obtained without f-NC, in contrast, 20 wt% Pt/C shows 0.95 V onset potential and 0.83 V half-wave potential. The f-NC@FeCo-NC catalyst also shows excellent Al-air battery performance when applied as cathode, which possesses a high open circuit voltage of 1.91 V and a high peak power density of 241 mW cm−2. We believe this sacrificial f-NC can be applied as general template for the fabrication of other hollow-structured carbon-based materials for broad electrochemical applications. [ABSTRACT FROM AUTHOR]

Supportive atomic Zn electrocatalysts exhibit excellent stability for oxygen reduction reaction (ORR) due to their fully occupied d orbitals of Zn, but their catalytic activity is not satisfactory. Whereas heteroatom doping can anchor the Zn atoms to achieve higher Zn loading; and additionally serve as auxiliary sites to enhance the catalytic activity of Zn sites. Herein, we present a method for the synthesis of N, S co-doped carbon with highly dispersed Zn (named Zn-NSC). The ORR activity of the Zn-NSC catalysts is optimized by adjusting the pyrolysis temperature and the atomic structure of the dopant molecules. The optimized Zn-NSC demonstrates significantly enhanced ORR electrocatalytic activity, this is attributable to its highly co-doping of N and S heteroatoms that are adjacent to Zn atoms. Specifically, the Zn-NSC 3 catalyst exhibits remarkable ORR characteristics with excellent onset voltage (0.97 V vs RHE) and half-wave potential (0.87 V vs RHE), surpassing those of Pt/C (0.97 V and 0.85 V, respectively). Additionally, the Zn-NSC 3 can be utilized as efficient cathode for Al-air batteries, achieving a high power density of 119.4 mW cm−2 and satisfactory discharge stability. This work proposes an approach for synthesizing low-cost and efficient ORR electrocatalysts for Al-air battery applications. • The Zn-NSC were synthesized through hydrothermal reaction and pyrolysis process. • The Zn-NSC 3 has a high doping level of N and Zn, with 32.4 and 2.6 at%, respectively. • The Zn-NSC 3 exhibits onset voltage (0.97 V) and half-wave potential (0.87 V), superior to Pt/C. • The Zn-NSC 3 assembled Al-air battery delivers high cell voltages and large powers. [ABSTRACT FROM AUTHOR]

Developing metal-free carbon electrocatalysts with atomically precise structures of hetero-doping is crucial for inventing reliable alternatives to precious metal-based catalysts. Our study reveals that the optimal active site is the edge-exposed N-neighbored carbon site in a chained N- C -C-S structure. Carbon material with N- C -C-S functional doping is controllably synthesized through polymer dehalogenation and heteroatom doping with thiomorpholine at room temperature. The resulting N/S-co-doped carbon with N- C -C-S functionalization, named N-C 2 -S, exhibits excellent ORR performance compared to other types of N, S-co-doped carbon, and commercial Pt/C. Typically, the N-C 2 -S sample shows the earliest onset potential of 0.96 V and a high half-wave potential of 0.85 V for promoting ORR. Assembled into an Al-air battery, The N-C 2 -S delivers an exceptional open-circuit voltage of 1.95 V and a large specific power of 128.1 mW cm 2. The synthesis strategy developed in this work can potentially open up precise functionalization of synthetic carbons with heteroatoms. [Display omitted] • The C site near the N in N-C-C-S is identified as highly active for oxygen reduction. • Different types of N, S-co-doped carbon are obtained via dehalogenation of PVDC. • N-C-C-S doping is realized via dehalogenation coupling reaction with thiomorpholine. • The N-C 2 -S sample exhibits exceptionally good oxygen reduction reaction performance. • The N-C 2 -S-assembled Al-air battery delivers high cell voltages and large powers. [ABSTRACT FROM AUTHOR]

• CeO 2 nanocubes efficiently catalyze 2e− ORR at the cathode and 2e− WOR at the anode. • CeO 2 NCs deliver high selectivity of 83% and faradic efficiency of 95.3% for 2e− ORR. • CeO 2 NCs also achieve high efficiency of 66% for 2e- WOR. • CeO 2 NCs obtain a high H 2 O 2 yield of 4.6 mol g cat. −1 h−1 (FE>85%) in a flow cell. Synthesis of H 2 O 2 via 2e− O 2 reduction or 2e− H 2 O oxidation has been widely acknowledged as promising alteratives to the energy-intensive anthraquinone processes. Herein, we report that the 2e− O 2 reduction and 2e− H 2 O oxidation reactions, for the first time, can be efficiently promoted on CeO 2 (100) facets, while majority of previous CeO 2 materials are utilized overwhelmingly as catalyst substrates. Electrochemical measurements indicate that CeO 2 nanocubes (NCs) deliver very high H 2 O 2 selectivity of 83% and faradic efficiency of 95.3% for 2e− O 2 reduction. Its H 2 O 2 yield rate at 0.5 V (vs. RHE) reaches 632 mmol g cat −1 h−1, which exceeds the performance of facet-unspecified CeO 2 nanodots (NDs) in this work and many noble metal- or carbon-based electrocatalysts in previous literatures. Furthermore, it also shows a high efficiency of 66% for 2e− H 2 O oxidation. When assembled into flow cell reactor, the CeO 2 NCs can obtain a total H 2 O 2 yield of 4.6 mol g cat. −1 h−1, and manage stable faradic efficiency (> 85%) in wide voltage range. Our work may inspire further investigation of rare earth metal oxide-based materials for 2e− oxygen electrocatalysis. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The fundamental understanding of electrocatalyst interactions at interfacial level for ORR is provided. • The chemistry and recent development in electrocatalytic ORR are explored. • The strategies for benchmarking electrocatalysts' performance are highlighted. • Future aspects of electrocatalyst interactions at interfacial level are discussed. The cathode process, oxygen reduction reaction (ORR), is crucial for producing green and reliable energy from the reorganization of chemical bonds in fuel cells. However, the application of ORR is limited due to its inefficiency, which can not only be attributed to the linearity of ORR intermediates binding energies (E b *OOH, E b *O, E b *OH) on the catalyst's active site (represented as *) but also to the serious influences of the watery environment on active sites. In an aqueous environment, catalyst interactions, including covalent, ionic, and van der Waals forces, at the interfacial level are critical in determining the catalytic activity and can considerably alter the kinetics and selectivity of ORR. Therefore, the interfacial confinement's unique properties can provide exciting new possibilities for designing molecular as well as material-based catalysts for ORR. Although several published reviews have focused on developments in interfacial engineering for electrocatalysis, not specifically for ORR, this domain still lacks an inclusive debate on the mechanism of interface structures during ORR. We highlighted the most recent employed strategies for interface structure construction and the role of interfacial interactions during ORR. Finally, the barriers and prospects for the construction of electrocatalysts based on such concepts as control of interfacial interactions, engineering, and technologies are also discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A catalyst-free approach was adopted to prepare a large conjugated poly-FePc. • Spectroscopic investigations confirmed the existence of FePc moieties in the prepared poly-FePc catalyst. • Poly-FePc displayed superior ORR performance in terms of activity, durability, and methanol tolarance. • DFT calculations indicated the down-shift in eg-orbital energy of FePc to facilitate ORR. Although Fe-phthalocyanine (FePc) has undergone extensive chemical modifications to realize improved oxygen reduction reaction (ORR), its superior performance has yet to be demonstrated at a practical level. Herein, a conjugated poly-FePc was prepared via microwave-assisted polymerization of 1,2,4,5-tetracyanobenzene in presence of FeCl 2. The characterization results of multiple spectroscopic techniques indicated that poly-FePc and monomeric FePc possessed similar structural features, proving that the polymerization process was successful. Further, the prepared poly-FePc was tested for ORR in 0.1 M KOH electrolyte and compared with the traditional 20% Pt/C and monomeric FePc catalysts. Poly-FePc was found to be the best ORR catalyst among studied electrocatalysts, displaying 258 and 40 mV positive shifts in half-wave potential compared with FePc and 20% Pt/C, respectively. The theoretical studies suggested that the large conjugation in poly-FePc down-shifted the energy of the dz2-orbital of Fe closer to the π*-orbital of O 2 (as also supported by the anodic shift in Fe3+/Fe2+ redox potential after polymerization), which allowed for an optimal coupling between these orbitals and therefore followed the 4e- ORR pathway. This study found that adjusting the electronic structures of the active sites of electrocatalysts might have improved their performance. [ABSTRACT FROM AUTHOR]