Catalyst For Zn-air Batteries Research Articles

N, S co-doped hollow carbon nanocages confined Fe, Co bimetallic sites for bifunctional oxygen electrocatalysis

Regulating pore architecture and electronic structure is of significance for improving oxygen electrocatalytic activity of M−N−C catalysts. Herein, N, S co-doped hollow carbon nanocages confined Fe, Co bimetallic sites (FeCo-NS-HNCs) are constructed through an efficient surface bridging strategy. The surface modifier of trithiocyanuric acid trisodium salt bridges Co doped ZIF-8 surface with Fe ions to promote the formation of Fe/Co-Nx sites. The synergistic coupling of metal sites and N, S co-doping manipulates the adsorption/desorption characteristics of M−Nx sites to optimize intrinsic activity. The Kirkendall effect constructs the hollow carbon nanocages, improving the accessibility of M−Nx sites. Benefiting from the ameliorated electronic structure and hollow porous architecture, FeCo-NS-HNCs displays excellent bifunctional oxygen electrocatalytic activity (ΔE = 0.655 V). The liquid and flexible Zn-air batteries of FeCo-NS-HNCs offer prominent power density and cycling stability. This work provides estimable insights into the structure design and activity regulation of M−N−C catalysts for Zn-air battery.

Hierarchical CoFe@N‐Doped Carbon Decorated Wood Carbon as Bifunctional Cathode in Wearable Zn‐Air Battery

Rechargeable Zn‐air batteries (ZAB) have drawn extensive attention due to their eco‐friendliness and safety. However, the lack of high‐performance and low‐cost oxygen redox reactions (OER and ORR) catalysts has become one of the main stumbling blocks in their development. Herein, we successfully fabricate a CoFe nanobubble encapsulated in nitrogen‐doped carbon nanocage on wood carbon support (CoFe@NC/WC) via pyrolysis of a novel Prussian blue analog (PBA)/spruce precursor. The hierarchical CoFe@NC/WC catalyst exhibits an excellent potential difference of 0.74 V between the OER potential at 10 mA cm−2 and half‐wave potential of ORR in 0.1 M KOH, comparable to recently reported preeminent electrocatalysts. Further, CoFe@NC/WC shows outstanding electrochemical performance in liquid ZAB, with a peak power density of 138.9 mW cm−2 and a specific capacity of 763.5 mAh g−1. More importantly, a bacterial cellulose nanofiber reinforced polyacrylic acid (BC‐PAA) hydrogel electrolyte shows ultrahigh tensile‐breaking stress of 1.58 MPa. In conjunction with the as‐prepared CoFe@NC/WC catalyst, BC‐PAA‐based wearable ZAB displays impressive rechargeability and foldability, and can power portable electronics, such as electronic timer and mobile phone, in bent states. This work provides a new approach toward high‐activity and low‐cost catalysts for ZAB.

Zn/N/S Co-doped hierarchical porous carbon as a high-efficiency oxygen reduction catalyst in Zn-air batteries.

Zn-N-C catalysts have garnered attention as potential electrocatalysts for the oxygen reduction reaction (ORR). However, their intrinsic limitations, including poor activity and a low density of active sites, continue to hinder their electrocatalytic performance. In this study, we have devised a dual-template strategy for the synthesis of Zn, N, S co-doped nanoporous carbon-based catalysts (Zn-N/S-C(S, Z)) with a substantial specific surface area and a graded pore structure. The introduction of S enhances electron localization around the Zn-Nx active centers, facilitating interactions with oxygen-containing substances. The resulting Zn-N/S-C(S, Z) sample exhibits outstanding performance in an alkaline solution, demonstrating a half-wave potential of 0.89 V. This value surpasses that of commercial Pt/C by 40 mV. Furthermore, when combined with RuO2 (Zn-N/S-C(S, Z) + RuO2), the catalyst demonstrates exceptional performance in a Zn-air battery, offering an open-circuit voltage (OCV) of 1.47 V and a peak power density of 290.8 mW cm-2. This study paves the way for the development of highly dispersed and highly active Zn-metal site catalysts, potentially replacing traditional Pt-based catalysts in various electrochemical devices.

Pt/C as a bifunctional ORR/iodide oxidation reaction (IOR) catalyst for Zn-air batteries with unprecedentedly high energy efficiency of 76.5%

Rechargeable Zn-air batteries (ZABs) are promising for energy storage and conversion. However, the low energy efficiency caused by the high charging voltage greatly hinders their commercialization. Herein, potassium iodide (KI) is introduced to ZABs to change the oxidation pathway from the sluggish oxygen evolution reaction (OER) to I- oxidation reaction (IOR) with faster kinetics and lower oxidation potential. Unexpectedly, the commercial carbon-based catalyst Pt/C with poor OER activity exhibits remarkable IOR activity. Benefitting from its high oxygen reduction reaction (ORR) activity, the fabricated ZABs deliver a low charging voltage of 1.68 V, high energy efficiency of 76.5%, and long cycle life of over 80 h at 5 mA cm−2. Density functional theory (DFT) calculation is conducted to reveal the IOR catalytic mechanism of the Pt/C catalyst. This work will reverse the traditional mindset on catalyst selection from ORR/OER to ORR/IOR and boost the commercialization of rechargeable ZABs.

Facile Preparation of Fe–N–C Oxygen Reduction Electrocatalysts from Metal Organic Frameworks for Zn-Air Battery

It is critical to study efficient, stable oxygen reduction reaction (ORR) electrocatalysts due to insufficient stability and expensive price of Pt/C catalysts for Zn-air batteries. Fe–N–C electrocatalysts was synthesized by a facile solvent-green method and the efficiency of Fe–N–C optimized was studied as potential ORR electrocatalysts under alkaline condition. Results indicated that it had excellent ORR activity with E1/2 of 0.93 V, which was competitive to that of Pt/C-JM under the same conditions. Moreover, the assembled Zn-air battery exhibited discharge potential and charge potential of 1.2 V, 2.32 V at 5 mA cm−2 with high stability, respectively. Overall, all results illustrated that Fe–N–C is an excellent ORR electrocatalyst in the field of metal air battery. Additionally, this work opens a good way to synthesize highly efficient electrocatalysts from metal organic framework and to investigate ORR mechanism of efficient chemical energy to electricity conversion.

Porous Cube-Shaped NiCoS <sub><i>x</i></sub>/CoS <sub>2</sub> Acts as Tri-Functional Catalyst for Zn-Air Battery and Overall Water Splitting

Porous Cube-Shaped NiCoS <sub><i>x</i></sub>/CoS <sub>2</sub> Acts as Tri-Functional Catalyst for Zn-Air Battery and Overall Water Splitting

Porous Cube-Shaped Nicos X /Cos2 Acts as Tri-Functional Catalyst for Zn-Air Battery and Overall Water Splitting

Porous Cube-Shaped Nicos X /Cos2 Acts as Tri-Functional Catalyst for Zn-Air Battery and Overall Water Splitting

Three-Dimensional Hierarchical Conductive Metal-Organic Frameworks/Nife Layered Double Hydroxide/Carbon Nanofibers: An Efficient Oxygen Reduction Reaction Catalyst for Zn-Air Batteries

Three-Dimensional Hierarchical Conductive Metal-Organic Frameworks/Nife Layered Double Hydroxide/Carbon Nanofibers: An Efficient Oxygen Reduction Reaction Catalyst for Zn-Air Batteries

Red Bean Pod Derived Heterostructure Carbon Decorated with Hollow Mixed Transition Metals as a Bifunctional Catalyst in Zn-Air Batteries.

Design and synthesis of low-cost and efficient bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in Zn-air batteries are essential and challenging. We report a facile method to synthesize heterostructure carbon consisting of graphitic and amorphous carbon derived from the agricultural waste of red bean pods. The heterostructure carbon possesses a large surface area of 625.5 m2 g-1 , showing ORR onset potential of 0.89 V vs. RHE and OER overpotential of 470 mV at 5 mA cm-2 . Introducing hollow FeCo nanoparticles and nitrogen dopant improves the bifunctional catalytic activity of the carbon, delivering ORR onset potential of 0.93 V vs. RHE and OER overpotential of 360 mV. Electron energy-loss spectroscopy (EELS) O K-edge map suggests the presence of localized oxygen on the FeCo nanoparticles, suggesting the oxidation of the nanoparticles. Zn-air battery with these carbon-based catalysts exhibits a peak power density as high as 116.2 mW cm-2 and stable cycling performance over 210 discharge/charge cycles. This work contributes to the advancement of bifunctional oxygen electrocatalysts while converting agricultural waste into value-added material.

Exploiting encapsulated FeCo alloy decorated N-doped hierarchically porous carbon electrocatalysts in rechargeable Zn-air batteries

Abstract Exploiting highly active non-noble metal catalyst with designed nanoarchitecture is essential and formidable for the rechargeable Zn-air batteries (ZABs). To this end, hierarchically porous N-doped carbon hybrids with encapsulated FeCo alloy (FeCo@NC) is designed by template-assisted method. The optimized sample pyrolyzed at 800 °C (FeCo@NC800) possesses a large specific surface area of 1195 m2 g−1, plentiful micro-/meso-/macro-pores and is rich in defects and graphitic N-doped carbon atoms. These preeminent characteristics endow the catalyst with superior bifunctional oxygen electrocatalytic activities (ΔE = E10-E1/2 =852 mV) in alkaline electrolyte, as well as outstanding stability. As air-electrode catalyst in ZAB, FeCo@NC800 reveals high power density of 169 mW cm−2, excellent rechargeable property and cycling stability. Moreover, the as-obtained catalyst displays promising application potentiality in solid-state ZAB.

Metal Phthalocyanine-Porphyrin-based Conjugated Microporous Polymer-derived Bifunctional Electrocatalysts for Zn-Air Batteries.

Conjugated microporous polymers (CMPs) as emerging porous materials with diverse structures and tunable building-units have attracted much attention in the electrochemical field. Herein, we designed phthalocyanine-porphyrin-based conjugated microporous polymers as precursors for fabrication of Co, Fe, N tri-doped graphene composites towards oxygen reduction and evolution reaction (ORR/OER). As expected, the elements cobalt and iron are well dispersed in graphene carbon and interact with the nitrogen sites, thereby providing extra electrocatalytic active sites and enhancing its overall conductivity. Benefiting from its unique design and structure, the obtained catalyst affords a superior bifunctional catalytic activity with a positive onset potential of 0.957 V for ORR, and a low overpotential of 0.36 V for OER. More attractively, the CoFeNG is employed as an air cathode catalyst in Zn-air batteries, showing a maximum current density of 215 mA cm-2 and good cycle stability for 20000 s. The rational design of phthalocyanine-porphyrin-based derivatives provides a feasible route for the construction of high-performance ORR/OER catalysts.

Iron-nitrogen doped carbon with exclusive presence of FexN active sites as an efficient ORR electrocatalyst for Zn-air battery

In this work, we have found that a new Fe-N module, FexN (x = 2, 3, or 4), in which the N atoms insert the lattice of Fe matrix, also has high catalytic activity towards ORR. We synthesized the FexN module embedded N-doped carbon material (FexN/NC) via a facile metal-organic framework (MOF)-templated approach. The as-synthesized FexN/NC shows a superb catalytic ORR activity as well as high methanol tolerance. The highly efficient catalytic active sites (FexN module and well-doped N species) were mainly responsible for the superb ORR activity. The synergistic mechanisms of the N-doped carbon support and FexN moieties for ORR at molecular level were elucidated by density functional theory calculations. The excellent catalytic ORR performance make the FexN/NC catalyst be a promising candidate to replace the expensive Pt based cathodic catalyst in Zn-air batteries.

In situ encapsulation of Co-based nanoparticles into nitrogen-doped carbon nanotubes-modified reduced graphene oxide as an air cathode for high-performance Zn-air batteries.

Exploring highly efficient catalysts for the oxygen reduction/evolution reaction (ORR/OER) is very important in rechargeable Zn-air batteries. N-doped carbon coupled with transition metal-based species are among the most promising cathode catalysts for Zn-air batteries. However, the aggregation of metal-based sites during the synthetic/cycling process is a serious drawback of these catalysts. Herein, in situ encapsulation of ultra-small Co/Co4N nanoparticles into N-doping carbon nanotubes (N-CNTs) anchored on reduced GO (Co/Co4N@N-CNTs/rGO) has been achieved through pyrolyzing a core-shell-structured ZIF-8@ZIF-67-modified GO (ZIF-8@ZIF-67/GO) precursor; the nanoparticles have been further applied as a bifunctional catalyst in Zn-air batteries. Benefitting from its uniform dispersion of Co-based particles, close contact of Co/Co4N species and N-CNTs, and high N content, Co/Co4N@N-CNTs/rGO shows outstanding catalytic activity/stability towards ORR and OER. Moreover, Zn volatilization and rGO introduction in Co/Co4N@N-CNTs/rGO can effectively promote the reactions of Zn-air cells. Hence, the Co/Co4N@N-CNTs/rGO-based conventional Zn-air battery exhibits a fantastic specific capacity of 783 mA h gZn-1, a continuous discharge platform over 6 days, a high-power density of ∼200 mW cm-2 and an ultra-long cycling life of 440 h with a small overpotential of ∼0.8 V. Moreover, a flexible Co/Co4N@N-CNTs/rGO-based Zn-air cell was also designed and revealed outstanding mechanical flexibility and good electrochemical performance, which suggests its potential application prospects in wearable electronic devices.

Sulfuration of an Fe–N–C Catalyst Containing FexC/Fe Species to Enhance the Catalysis of Oxygen Reduction in Acidic Media and for Use in Flexible Zn–Air Batteries

During the preparation of atomically dispersed Fe-N-C catalysts, it is difficult to avoid the formation of iron-carbide-containing iron clusters ("Fex C/Fe"), along with the desired carbon matrix containing dispersed FeNx sites. As a result, an uncertain amount of the oxygen reduction reaction (ORR) occurs, making it difficult to maximize the catalytic efficiency. Herein, sulfuration is used to boost the activity of Fex C/Fe, forming an improved system, "FeNC-S-Fex C/Fe", for catalysis involving oxygen. Various spectroscopic techniques are used to define the composition of the active sites, which include Fe-S bonds at the interface of the now-S-doped carbon matrix and the Fex C/Fe clusters. In addition to outstanding activity in basic media, FeNC-S-Fex C/Fe exhibits improved ORR activity and durability in acidic media; its half-wave potential of 0.821 V outperforms the commercial Pt/C catalyst (20%), and its activity does not decay even after 10 000 cycles. Interestingly, the catalytic activity for the oxygen evolution reaction (OER) simultaneously improves. Thus, FeNC-S-Fex C/Fe can be used as a high-performance bifunctional catalyst in Zn-air batteries. Theoretical calculations and control experiments show that the original FeNx active centers are enhanced by the Fex C/Fe clusters and the Fe-S and C-S-C bonds.

N, P‐doped CoS2 Embedded in TiO2 Nanoporous Films for Zn–Air Batteries

AbstractThe search for efficient and cost‐effective catalysts for bifunctional oxygen reduction and evolution reaction (ORR and OER) is highly demanded because of the sluggish four‐electron transfer involved redox reactions in Zn–air batteries (ZABs). Herein, (N, P) codoped CoS2 nanoclusters embedded inside TiO2 nanoporous films (denoted as N, P/CoS2@TiO2 NPFs) are synthesized as novel bifunctional ORR/OER catalysts for ZABs. The catalytic activity and stability are promoted by the (N, P)‐dopants due to the enhanced conductivity, increased active surface area, and facilitated reaction kinetics. The N, P/CoS2@TiO2 NPFs exhibit exceptional onset potentials of 0.91 and 1.41 V for ORR and OER, respectively. When used as cathodes in ZABs, the N, P/CoS2@TiO2 NPFs exhibit a reduced charge–discharge gap of 0.8 V at 10 mA cm−2 and a stable cycling performance over 130 h, surpassing the conventional Pt/C+IrO2 catalysts. Moreover, the assembled ZABs delivering a specific capacity of 610 mAh g−1 can be used for flexible devices. This work provides a path for the rational design of bifunctional electrocatalyst for ZABs.