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A simple pyrolysis route has been developed for fabrication of nitrogen-doped carbon networks (N-C net) that not only features a large number of mesoporous structures, but also holds high specific surface area and excellent conductivity. The as-developed N-C net performs impressively toward electrocatalysis of oxygen reduction reaction (ORR) and CO 2 reduction reaction (CO 2 RR). For ORR in alkaline electrolyte, the N-C net manifests an initial potential of 0.95 V and half-wave potential of 0.86 V that are comparable to the benchmarked Pt/C catalysts. While for CO 2 RR, the N-C net shows a high selectivity for CO production with Faraday efficiency (FE) of as high as 95% and long-term stability. We further demonstrate the potential application of N-C net in electrochemical devices of zinc-air batteries (ZABs) and microbial CO 2 electrolysis cell (MEC), the former is capable of releasing a maximum power density of 141 mW cm-2, while the later shows capability for efficiently converting CO 2 into CO with the assistance of external voltage. We thus propose and set up an integrated proof-of-concept electrochemical device with ZABs driving MEC that can implement the feasibility of self-powered conversion of CO 2 to value-added CO. [Display omitted] • The N-doped carbon networks prepared by one-pot pyrolyzing ZIF-8 exhibited excellent electrocatalytic properties toward oxygen reaction reduction and CO 2 reduction. • Catalyzed by the cathodic bifunctional N-doped carbon networks, the Zn-air batteries and microbial CO 2 electrolysis cell with favorable performance were assembled in this work. • A coupled electrochemical device with ZABs driving MEC was firstly proposed and achieved self-powered conversion of CO 2 to value-added CO. [ABSTRACT FROM AUTHOR]

Optimized electrocatalyst that hybrids with carbon coating FeCoP x nanoparticles possesses catalytic activity toward ORR, OER and HER. Furthermore, through the design of alkali-acid electrolyzer and device integration, for the very first time, a single Zinc-air battery enable to drive an alkali-acid electrolyzer for producing hydrogen and oxygen. [Display omitted] • A one-pot scalable pyrolysis strategy to fabricate a tri-functional electrocatalyst. • High catalytic activity toward ORR&OER in alkaline and HER in acidic media. • The Zn-air battery can run stably for 1500 cycles. • An alkali-acid electrolyzer only requires 0.99 V to release an electrolysis current density of 10 mA cm−2. • A single self-made Zinc-air battery can drive an alkali-acid electrolyzer to produce hydrogen. Developing handy synthesis routes to fabricate low-cost, high-activity, and multifunctional electrocatalysts for a variety of electrochemical reactions is highly desirable so as to achieve the goal that one catalyst can be used for integrated electrolysis devices, thus greatly simplifying the electrocatalyst system processing. Here, we report a one-pot scalable pyrolysis strategy to fabricate a tri-functional electrocatalyst, i.e. , hybrids with carbon coating FeCoP x nanoparticles, which shows favorable electrocatalytic properties toward oxygen reduction reaction, oxygen evolution reaction in alkaline solution, and hydrogen evolution reaction in acidic condition. The new synthesis routes enable us to readily develop an integrated device with a Zn-air battery driving an alkali-acid electrolyzer by just using one catalyst. The present work may shed light on the practical viability of the development of multifunctional electrocatalysts for integrated devices applications. [ABSTRACT FROM AUTHOR]

Transition metal carbide catalysts are the alternative products of traditional noble metal Pt/C in oxygen reduction reaction (ORR). Oleic acid-coated iron oxide nanoparticles (F 3 O 4 @OA) was prepared by pyrolysis, assembled with reduced graphene oxide (rGO), and carbonized at 800 °C to obtain N doped iron carbide nanoparticles supported rGO (N–Fe 3 C/rGO). The particle size of nanocrystals increases significantly with the graphene loading risen can be seen in the transmission electron microscope (TEM) image which roughly distributed around 40 nm. The linear scanning voltammetry (LSV) curve shows the material has an ORR performance equivalent to Pt/C in alkaline media. • Controllable supported Fe 3 C nanocrystals on rGO. • Enhanced electrochemical performance by proportion Fe 3 C on rGO. • Remarkably enhanced ORR performance. [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]

Microbial fuel cells (MFCs) is a device that uses microorganisms as biocatalysts to directly convert the chemical energy of waste organic into electrical energy. The sluggish kinetics and the high cost of oxygen reduction reaction (ORR) are the major factors hindering the development of MFCs, especially in neutral electrolyte that is widely used in common MFCs. Therefore, it is highly desirable either to explore cheap cathode ORR catalysts with high catalytic activity and stability, or to develop newly MFCs system that can significantly enhance cathode kinetic. In this study, we develop a metal-free N/B-co-doped carbon-based catalyst (denoted as PANI/B-8) by pyrolysis of mixtures of polyaniline and boric acid, which show remarkably improved kinetic and activity toward ORR in alkaline electrolyte relative to neutral electrolyte, inspiring us to develop an asymmetric neutral-alkaline microbial fuel cell (ANA-MFCs) with microbial as neutral anode catalysts and PANI/B-8 as alkaline cathode catalysts, between the two chambers are separated by a proton exchange membrane (PEM) to prevent mixing of anolyte and catholyte while to ensure ion conductivity. The present ANA-MFCs notably deliver an output power density twice higher than that of the symmetric MFCs, thanks to the remarkably enhanced ORR kinetic in alkaline cathode reaction. The asymmetric neutral-alkaline microbial fuel cell with N/B Co-doped carbon exhibits prominent battery performance compared to conventional neutral-neutral device. And it delivers a current value twice higher than that of the symmetric device, thanks to the remarkably enhanced ORR kinetic in alkaline cathode reaction. [Display omitted] [ABSTRACT FROM AUTHOR]

• Ni@NiO-Cu@CuO/NCS is prepared from MOF material via direct calcination process. • Material favors to human urine urea oxidation and groundwater NO 3 − reduction. • Presence of M2+/M3+ redox couple offers better bifunctional catalytic activity. • Substitution of ORR with NRR launches a new branch of fuel cell named UNFC. Though direct urea fuel cells (DUFCs) show promising potential for green energy generation, the practical feasibility of its on-site installation is yet encumbered by the sluggish electrokinetics and low-value product (H 2 O) of oxygen reduction reaction (ORR). We here report the design and synthesis of a bifunctional hybrid electrocatalyst of nitrogen-doped carbon sheets supporting Ni@NiO-Cu@CuO composites (Ni@NiO-Cu@CuO/NCS) via direct calcination of Ni- and Cu-containing metal organic frameworks (MOFs). The as-derived nanohybrid shows impressively high catalytic performance towards urea oxidation reaction (UOR) in alkali and nitrate reduction reaction (NRR) in acidic electrolyte, which inspire us to set up a urea-nitrate fuel cell (UNFC). Owing to the excellent electrochemical characteristics behaviour of prepared nanostructures, the fabricated UNFC simultaneously exhibits improved fuel cell performance of 22.55 ± 2.3 mW cm−2 and degrade the urine and nitrate at the anode and cathode, respectively. The presented innovative electrochemical device may open up a prime step for the development of renewable UNFC for simultaneous green energy generation and N-containing waste removal. [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]

The electrocatalytic oxygen reduction reaction (ORR) and carbon dioxide reduction reaction (CO 2 RR) are considered as major strides for the development of a global-scale sustainable energy system, owing to their potential in neutralizing carbon emissions, generating value-added product, and delivering clean energy. However, the practicability of ORR and CO 2 RR is hampered by the sluggish kinetics and instability of the catalyst materials, calling for thirst for exploring efficient and stable electrocatalyst. With this concern, we herein report a hybrid (c-CoACC/CNTs) with carbon nanotubes (CNTs) decorating cubic cobalt amide cyanide complex (c-CoACC), which is synthesized by using molten salt (MS) assisted method and exhibits highly crystalline and thermally stable features. The c-CoACC/CNTs exhibit profound ORR activity with the onset and half-wave potential (E 1/2) of 0.972 and 0.87 V in alkaline conditions, respectively. The practical application of c-CoACC/CNTs as ORR catalysts has been verified in a home-made zinc-air battery, which is capable of releasing a maximum power density of 188 mW cm−2 in comparison with 175 mW cm−2 in the Pt/C based zinc-air battery. Furthermore, the c-CoACC/CNTs exhibits desirable electrocatalytic properties toward CO 2 -to-CO conversion in 0.5 M KHCO 3 with a tunable production ratio between CO and H 2 , yielding a maximum Faraday efficiency of 83.8% at −0.78 V vs. RHE. The attractive electrocatalytic properties in the c-CoACC/CNTs can be attributed to the improved electroactive sites relative to individual c-CoACC and CNT, reduced diffusion resistance, and enhanced three-phase boundaries. Notably, the c-CoACC/CNTs perform encouraging stability in the catalysis of ORR and CO 2 RR under various electrochemical regimes and conditions, directing a viable path for a future global-scale sustainable energy system. [ABSTRACT FROM AUTHOR]