Electrocatalysts For Zn-air Batteries Research Articles

Electrospinning-derived transition metal/carbon nanofiber composites as electrocatalysts for Zn-air batteries.

The sluggish kinetics of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) significantly impede the broader implementation of Zn-air batteries (ZABs), underscoring the necessity for advanced high-efficiency materials to catalyze these electrochemical processes. Recent advancements have highlighted the potential of transition metal/carbon nanofiber (TM/CNF) composite materials, synthesized via electrospinning technology, due to their expansive surface area, profusion of active sites, and elevated catalytic efficacy. This review comprehensively examines the structural characteristics of TM/CNFs, with a particular emphasis on the pivotal role of electrospinning technology in fabricating diverse structural configurations. Additionally, it delves into the mechanistic underpinnings of various strategies aimed at augmenting the catalytic activity of TM/CNFs. A meticulous discourse is also presented on the application scope of TM/CNFs in the realm of electrocatalysis, with a special focus on their impact on the performance of assembled ZABs. Lastly, this review encapsulates the challenges and future prospects in the development of TM/CNF composite materials via electrospinning, aiming to provide an exhaustive understanding of the current state of research in this domain and to foster further advancements in the commercialization of ZABs.

Pyrolysis-free cobalt porphyrin coordination polymer as electrocatalyst for Zn-air batteries and water splitting

The development of high-performance and stable trifunctional electrocatalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) plays key role in the practical application of renewable energy systems. Herein, we report a pyrolysis-free synthesis of a CoNC based porphyrin cobalt coordination polymer electrocatalyst by using 5,10,15, 20-tetrad-[4′-(terpyridinyl) phenyl] porphyrin and cobalt bivalent ions. The polymer exhibits pronounced trifunctionality at a low ORR onset potential of 0.87 V vs. RHE, and an overpotentials of 378 and 210 mV at 10 mA cm−2 for the OER and HER with substantial stability in alkaline media. In the constructed aqueous Zn-air battery, it displays satisfied specific capacity of 723 mAh g−1 and appreciable stability for 85 h. Density functional theory computations reveal that TTBPP-Co exhibits excellent donor–acceptor characteristics with HOMO-LUMO band gap of 1.87 eV. This work provides a new design of metal porphyrin coordination polymers as efficient trifunctional electrocatalysts for clean energy applications.

CuO/Co3O4 heterostructures with carbon nanotubes composites as ORR/OER electrocatalysts for Zn-air batteries

Rechargeable Zn-air batteries (ZABs) constitute promising next-energy conversion and storage systems due to their low cost, intrinsic safety, and feasibility to fabricate high energy density and stable charge and discharge voltage. Nevertheless, the most significant challenge of rechargeable ZABs is relatively high over potential owing to the sluggish kinetics of oxygen reactions on the air cathode, requiring high-performance noble-metal-free bifunctional electrocatalysts with highly cost-effective. Herein, we developed a facile and scalable coprecipitation strategy to successfully prepare CuO/Co3O4@CNTs catalysts for bifunctional oxygen electrocatalysts. This unique strategy enables CuO/Co3O4 nanoparticles to be uniformly grown on CNTs and the simultaneous pyrolysis process results in the generation of ultrafine CuO/Co3O4 heterostructures. Contributed to an abundance of heterostructures, the oxygen vacancies and unsaturated chemical bonds in the interface were generated in CuO/Co3O4. Consequently, the CuO/Co3O4@CNTs delivered bifunctional activity of ΔE of 0.78 V and good stability that can maintain 1000 h charge and discharge cycles.

NaCl sealing Strategy-Assisted synthesis CoO-Co heterojunctions as efficient oxygen electrocatalysts for Zn air batteries

Developing highly efficient, low-cost, and stable bifunctional oxygen electrocatalysts is essential for the wide popularization of rechargeable Zn-air batteries. Combining zero-dimensional metal nanoparticles with two-dimensional metal oxide nanosheets is an appealing strategy to balance performance and cost. However, the precise construction of these composites remains a great challenge, and their interaction mechanisms lack thorough study. Herein, a cobalt-oxide-based bifunctional oxygen electrocatalyst comprising a rich Co-CoO heterointerface (CoO/Co@NG) was synthesized via a NaCl sealing-assisted pyrolysis strategy. The NaCl crystals played the role of a closed nanoreactor, which facilitated the formation of a CoO-Co heterojunction. Experimental results and theoretical calculations confirmed that the ingeniously constructed heterojunction expedited the oxygen reduction reaction and oxygen evolution reaction kinetics, which is superior to Pt/C. When serving as the air electrode in an assembled liquid-state Zn-air battery, the battery shows high power density (215 mW cm−2), specific capacity (710 mAh gzn−1), and outstanding durability (720 h at 10 mA cm−2). This work provides an innovative avenue to design high-performance heterojunction electrocatalysts for perdurable Zn-air batteries.

Tuning the coordination environment of Fe atoms enables 3D porous Fe/N-doped carbons as bifunctional electrocatalyst for rechargeable zinc-air battery

As one of the most promising candidates for power sources, the rechargeable Zn-air batteries have attracted much attention due to their high energy density. However, Zn-air batteries suffer from sluggish kinetics of oxygen reduction (ORR) and oxygen evolution reaction (OER) during the discharge and charge process. Herein, a FeN2-doped carbon with a unique three-dimensional (3D) porous structure (CeO2-FeNC-5) was synthesized as an electrocatalyst for Zn-air batteries by one-step pyrolysis and introducing CeO2 to tune the coordination environment of Fe atoms. Extended X-ray absorption fine structure (EXAFS) results indicate that the introduction of CeO2 can convert FeN3 moieties into FeN2 moieties. The CeO2-FeNC-5 exhibits a more positive half-wave potential of 0.902 V for ORR, and a low overpotential of 0.327 V at 10 mA cm−2 for OER. Furthermore, the Zn-air battery with CeO2-FeNC-5 achieve a maximum power density (169 mW cm−2), a high open voltage platform (1.47 V) and superior cycling stability (200 h). The unique 3D porous structure provides channels for mass transport and exposes sufficient active sites to facilitate the ORR and OER processes. Calculations prove that FeN2 moieties are beneficial to O2 adsorption on Fe/N-doped carbon surface. This work provides an effective strategy for designing and synthesizing FeNx-doped carbon matrix electrocatalysts for sustainable metal-air batteries.

Trace Level Co Modified Ticn-Bcnnts as an Efficient Orr Electrocatalyst for Zn-Air Batteries

Trace Level Co Modified Ticn-Bcnnts as an Efficient Orr Electrocatalyst for Zn-Air Batteries

Facile synthesis of ZnS decorated N, S co-doped carbon polyhedron as high efficiency oxygen reduction reaction catalyst for Zn-air battery

Developing low cost, environmentally friendly and high efficiency oxygen reduction reaction (ORR) electrocatalysts is critical for clean energy conversion and storage devices including fuel cells and metal-air batteries. Herein, we developed a facile method to doping N, S and ZnS into carbon framework simultaneously. The N, S co-doping and extra ZnS active sites could prominently enhance the ORR performance of the carbon. The optimized sample ZnS@NC-3 exhibit an onset potential of 0.94 V and a half-wave potential of 0.84 V, which is comparable to 20 wt% Pt/C. In addition, the methanol tolerance and cycle ability are obvious superior than that of Pt/C. Moreover, when used as electrocatalysts for Zn-air battery, the battery exhibits an open circuit voltage of 1.524 V, a high specific capacity of 736 mA h g−1 and a max power density of 176 mW cm−2, demonstrating its great potential for clean energy conversion.

Two-Dimensional Hierarchical Fe–N–C Electrocatalyst for Zn-Air Batteries with Ultrahigh Specific Capacity

Promoting the performance of Zn-air batteries urgently requires rational design of electrocatalysts with highly efficient mass and charge transfer capacity. In this study, two-dimensional (2D) hier...

Scalable solid-state synthesis of coralline-like nanostructured Co@CoNC electrocatalyst for Zn-air batteries.

A facile and scalable solid-state synthesis strategy is developed to produce hierarchical coralline-like nanostructured electrocatalysts with cobalt nanoparticles and Co-NX sites for efficient oxygen reduction reaction, opening up an avenue for the mass production of non-precious metal catalysts for metal-air batteries and fuel cells, etc.

Bifunctional Transition Metal Hydroxysulfides: Room-Temperature Sulfurization and Their Applications in Zn-Air Batteries.

Bifunctional electrocatalysis for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) constitutes the bottleneck of various sustainable energy devices and systems like rechargeable metal-air batteries. Emerging catalyst materials are strongly requested toward superior electrocatalytic activities and practical applications. In this study, transition metal hydroxysulfides are presented as bifunctional OER/ORR electrocatalysts for Zn-air batteries. By simply immersing Co-based hydroxide precursor into solution with high-concentration S2- , transition metal hydroxides convert to hydroxysulfides with excellent morphology preservation at room temperature. The as-obtained Co-based metal hydroxysulfides are with high intrinsic reactivity and electrical conductivity. The electron structure of the active sites is adjusted by anion modulation. The potential for 10 mA cm-2 OER current density is 1.588 V versus reversible hydrogen electrode (RHE), and the ORR half-wave potential is 0.721 V versus RHE, with a potential gap of 0.867 V for bifunctional oxygen electrocatalysis. The Co3 FeS1.5 (OH)6 hydroxysulfides are employed in the air electrode for a rechargeable Zn-air battery with a small overpotential of 0.86 V at 20.0 mA cm-2 , a high specific capacity of 898 mAh g-1 , and a long cycling life, which is much better than Pt and Ir-based electrocatalyst in Zn-air batteries.

Metal-Free Ketjenblack Incorporated Nitrogen-Doped Carbon Sheets Derived from Gelatin as Oxygen Reduction Catalysts

Electrocatalysts facilitating oxygen reduction reaction (ORR) are vital components in advanced fuel cells and metal-air batteries. Here we report Ketjenblack incorporated nitrogen-doped carbon sheets derived from gelatin and apply these easily scalable materials as metal-free electrocatalysts for ORR. These carbon nanosheets demonstrate highly comparable catalytic activity for ORR as well as better durability than commercial Vulcan carbon supported Pt catalysts in alkaline media. Physico-chemical characterization and theoretical calculations suggest that proper combination of graphitic and pyridinic nitrogen species with more exposed edge sites effectively facilitates a formation of superoxide, [O2(ad)](-), via one-electron transfer, thus increasing catalytic activities for ORR. Our results demonstrate a novel strategy to expose more nitrogen doped edge sites by irregular stacked small sheets in developing better electrocatalysts for Zn-air batteries. These desirable architectures are embodied by an amphiphlilic gelatin mediated compatible synthetic strategy between hydrophobic carbon and aqueous water.