Zn Catalysts Research Articles

Cubic core–shell structure of NiCoSx/CoS2 as a high-efficiency tri-functional catalyst for Zn–air battery and overall water splitting

Cubic core–shell NiCoSx/CoS2 composite catalyst was successfully prepared on the basis of K3[Co(CN)6], which exhibited an excellent bifunctional catalytic activity for ORR and OER, small ΔE values and long-term durability.

3d Interconnected Honeycomb-Like Multifunctional Catalyst for Zn–Air Batteries

3d Interconnected Honeycomb-Like Multifunctional Catalyst for Zn–Air Batteries

Low-temperature liquid reflux synthesis of core@shell structured Ni@Fe-doped NiCo nanoparticles decorated on carbon nanotubes as a bifunctional electrocatalyst for Zn–air batteries

Core@shell structured Ni@Fe-doped NiCo nanoparticles decorated on carbon nanotubes (Fe/Ni@NiCo-CNT) synthesized as an efficient and stable bifunctional ORR/OER catalyst for Zn–air batteries.

Fast acid-leaching strategy treated hollow cobalt–carbon materials as highly efficient electrochemical catalysts for Zn–air batteries

Metal–organic frameworks (MOFs) are employed as ideal calcining templates for the synthesis of highly efficient metal–carbon based oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts.

Three-dimensional hierarchical conductive metal–organic frameworks/NiFe layered double hydroxide/carbon nanofibers: an efficient oxygen evolution reaction catalyst for Zn–air batteries

The structural and compositional modulation of inexpensive hydroxides is not only important, but also an ongoing challenge for the preparation of efficient oxygen evolution reaction (OER) electrocatalysts.

Exploring the Zn-regulated function in Co–Zn catalysts for efficient hydrogenation of ethyl levulinate to γ-valerolactone

A series of CoZn catalysts supported on N-doped porous carbon (CoxZny@NPC-T) prepared at different calcination temperatures are studied for catalytic hydrogenation of biomass-based ethyl levulinate to γ-valerolactone, in which Zn is introduced as a regulator.

A stable single-atom Zn catalyst synthesized by a ligand-stabilized pyrolysis strategy for selective oxidation of C–H bonds

A ligand-stabilized pyrolysis strategy was developed to fabricate single atom dispersed Zn–N–C catalyst. The fabricated Zn–N–C-900 catalyst showed excellent photocatalytic activity and outstanding stability for ethylbenzene selective oxidation.

An ultrahigh-loading single-site Zn catalyst for efficient and ambient hydrogen generation from silanes.

A nitrogen-doped carbon-supported ultrahigh-loading single-site Zn catalyst (Zn1-N-C, 28.3 wt%) was facilely constructed by using a ball milling strategy. With atomically dispersed ZnN3O sites, the catalyst showed superior catalytic properties for the generation of H2 from silane/alcohol pairs, and scale-up and recycling tests demonstrated its great potential in practical applications.

Tailoring the Electronic Structure of an Atomically Dispersed Zinc Electrocatalyst: Coordination Environment Regulation for High Selectivity Oxygen Reduction

AbstractAccurately regulating the selectivity of the oxygen reduction reaction (ORR) is crucial to renewable energy storage and utilization, but challenging. A flexible alteration of ORR pathways on atomically dispersed Zn sites towards high selectivity ORR can be achieved by tailoring the coordination environment of the catalytic centers. The atomically dispersed Zn catalysts with unique O‐ and C‐coordination structure (ZnO3C) or N‐coordination structure (ZnN4) can be prepared by varying the functional groups of corresponding MOF precursors. The coordination environment of as‐prepared atomically dispersed Zn catalysts was confirmed by X‐ray absorption fine structure (XAFs). Notably, the ZnN4 catalyst processes a 4 e− ORR pathway to generate H2O. However, controllably tailoring the coordination environment of atomically dispersed Zn sites, ZnO3C catalyst processes a 2 e− ORR pathway to generate H2O2 with a near zero overpotential and high selectivity in 0.1 M KOH. Calculations reveal that decreased electron density around Zn in ZnO3C lowers the d‐band center of Zn, thus changing the intermediate adsorption and contributing to the high selectivity towards 2 e− ORR.

Tailoring the Electronic Structure of an Atomically Dispersed Zinc Electrocatalyst: Coordination Environment Regulation for High Selectivity Oxygen Reduction.

Accurately regulating the selectivity of the oxygen reduction reaction (ORR) is crucial to renewable energy storage and utilization, but challenging. A flexible alteration of ORR pathways on atomically dispersed Zn sites towards high selectivity ORR can be achieved by tailoring the coordination environment of the catalytic centers. The atomically dispersed Zn catalysts with unique O- and C-coordination structure (ZnO3 C) or N-coordination structure (ZnN4 ) can be prepared by varying the functional groups of corresponding MOF precursors. The coordination environment of as-prepared atomically dispersed Zn catalysts was confirmed by X-ray absorption fine structure (XAFs). Notably, the ZnN4 catalyst processes a 4 e- ORR pathway to generate H2 O. However, controllably tailoring the coordination environment of atomically dispersed Zn sites, ZnO3 C catalyst processes a 2 e- ORR pathway to generate H2 O2 with a near zero overpotential and high selectivity in 0.1 M KOH. Calculations reveal that decreased electron density around Zn in ZnO3 C lowers the d-band center of Zn, thus changing the intermediate adsorption and contributing to the high selectivity towards 2 e- ORR.

Electron-transfer enhanced sponge-like CrP-Re2P as a robust bifunctional electrocatalyst for high-current overall water splitting and Zn–H2O cell

Developing dual functions, high-performance and stable catalysts for simultaneous hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at high-current density is highly desirable but still remaining as a challenge. Herein, a porous sponge-like structure of CrP-Re2P composite was successfully constructed on nickel foam (NF) via a facile hydrothermal, drop casting, and subsequent phosphating treatment. Remarkably, the CrP-Re2P/NF exhibits extraordinary performance with an ultralow overpotential of 148 mV at a current density of 100 mA cm−2 for HER and 255 mV at 20 mA cm−2 for OER in 1.0 M KOH, respectively. In addition, the bifunctional catalyst also manifests high-efficiency overall water splitting performance that drives a two-electrode system with 500/1000 mA cm−2 at a voltage as low as 1.89/2.02 V in 30% KOH. Moreover, the overall water-splitting device can achieve superior durability for 100 h at a current density of 100 mA cm−2 without obvious degradation. More significantly, the CrP-Re2P/NF is used as the cathode of alkaline Zn-H2O cell with a power density of 8.8 mW cm−2 and robust stability for 180 h, indicating that the catalyst has an encouraging industrial perspective. The excellent electrocatalytic performance of CrP-Re2P/NF is mainly attributed to the porous structure exposing more active sites, high conductivity resulted better charge transfer, as well as the strong synergy between CrP and Re2P species to regulate the binding energy with reactant intermediates. The strategy provides a novel and feasible approach for the development of highly efficient and stable bifunctional catalysts for overall water splitting and Zn–H2O cell.

Fe,N-modulated carbon fibers aerogel as freestanding cathode catalyst for rechargeable Zn–Air battery

Freestanding air cathode catalyst with exceptional catalytic bifunctions for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is highly desirable for exploring rechargeable Zn–air batteries (ZABs) with low cost and high reliability. Here, a facile and scalable approach is demonstrated to prepare efficient and robust freestanding cathode catalyst that consists of dispersed Fe3C nanoparticles, rich Fe-Nx/N-C species and carbon fibers networks with large specific surface area, which is based on one-pot in-situ coupling of Fe and N induced active sites within bacterial cellulose-derived carbon fibers networks. Its bifunctional activity parameter (ΔE) for ORR and OER is 0.79 V, superior to those of single Fe- or N- modulated counterparts, and comparable to the state-of-the-art Pt/C + RuO2 catalyst (0.79 V). This material can be directly used as freestanding and binder-free catalyst layer, and as-assembled ZABs exhibit a larger peak power density (173 mW cm−2), higher specific capacity (717 mA h g−1, 10 mA cm−2) and better cycle stability (negligible activity decay after 165 h charge/discharge cycles) than those of Pt/C + RuO2-based devices, representing their potential applications in advanced energy conversion systems.

Relation Between Coordination and Lewis‐Acid Property of MOF‐Derived Mononuclear Zn(II) Catalyst Toward Epoxide Hydroxylation

AbstractLewis‐acid properties of the coordinatively unsaturated metal ions are highly relevant to the coordination environment; however, it remains a challenge to establish the coordination structure‐activity relationship, especially in heterogeneous catalysis. Here, a typical metal‐organic framework, ZIF‐8, is selected as the precursor to prepare Lewis‐acid based Zn−N/P−C mononuclear catalysts, with well‐designed external structures but difference in the local coordination. The obtained mononuclear Zn(II) catalysts can not only inherit the advantages of MOF in coordination, but also simulate the homogeneous environment during the catalysis owing to the monodispersed metal sites in ZIF‐8. Eventually, relation between coordination and Lewis‐acid property toward epoxide hydroxylation has been illustrated. Results show the substituted coordination atom of P and the decrease of coordination number strongly enhance the Lewis‐acidity of Zn2+, causing the TOF values changes from 8.7 to 80.1 h−1 based on Zn content. The work affords an understanding and inspiration of coordination environment matters toward Lewis‐acid catalysis in organic transformations.

Wood Carbon Based Single-Atom Catalyst for Rechargeable Zn–Air Batteries

Wood Carbon Based Single-Atom Catalyst for Rechargeable Zn–Air Batteries

CoNi Nanoparticles Supported on N-Doped Bifunctional Hollow Carbon Composites as High-Performance ORR/OER Catalysts for Rechargeable Zn-Air Batteries.

Searching for high-quality air electrode catalysts is the long-term goal for the practical application of Zn-air batteries. Here, a series of coexistent composite materials (CoNi/NHCS-TUC-x) of cobalt-nickel supported on nitrogen-doped hollow spherical carbon and tubular carbon are obtained using a simple pyrolysis strategy. Co and Ni in the composites are mainly present in the form of alloy nanoparticles, M-Nx and M-Cx (M = Co or Ni) species, with high oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) electroactivity. The materials containing different proportions of spherical carbon and tubular carbon obtained by simply adjusting the raw materials for generating tubular carbon exhibit interesting bifunctional performance: samples with an abundant tubular content have the highest ORR onset potential (0.91 V vs reversible hydrogen electrode), while those with a rich spherical content have the highest ORR current density (5.13 mA·cm-2). Furthermore, CoNi/NHCS-TUC-3 provides the lowest potential difference (ΔE = Ej=10 - E1/2) of 0.806 V. We then test the potential possibility of CoNi/NHCS-TUC-3 as an air electrode for primary and rechargeable Zn-air batteries. The primary battery delivers an open-circuit potential of 1.59 V, a peak power density of 361.8 mA·cm-2, and a specific capacity of 756.5 mA h·gZn-1. The rechargeable battery could be cycled stably for more than 55 h at 10 mA·cm-2. These characteristics make CoNi/NHCS-TUC-3 a superior electrocatalyst for both the ORR and OER, as well as a suitable bifunctional electrode applied to a rechargeable Zn-air battery.

3D MXene anchored carbon nanotube as bifunctional and durable oxygen catalysts for Zn–air batteries

The development of bifunctional activity and long durability of ORR/OER catalyst is vital for realizing the practical application of Zn–air batteries (ZAB). Herein, 3D-structured bifunctional catalysts, CoFe nanoalloy decorated carbon nanotubes (CNT) anchoring with 2D MXene (Fe/Co-CNT@MXene-T), were prepared and fabricated as the cathode for both aqueous and flexible ZAB. Taking advantages of active sites of CoFe nanoparticles, robust sheath and fast charge transfer provided by CNT and MXene, our optimal catalyst Fe/Co-CNT@MXene-8 exhibited remarkable electroactivities of ORR and OER comparable with the benchmark Platinum carbon (Pt/C) and Ruthenium dioxide (RuO2), respectively. The as-assembled aqueous ZAB with Fe/Co-CNT@MXene-8 as cathode exhibited a high specific capacity of 759 mA h g −1 at a current density of 10 mA cm−2, and a stable voltage platform in the quick discharge–charge test under a 375h long-lasting operation, superior to those assembled with benchmark commercial catalyst and other reported catalysts. Furthermore, the as-assembled flexible ZAB with Fe/Co-CNT@MXene-8 as cathode also presented excellent durability cycling and showed promising perspectives as future power sources for wearable application. Such high performance was also verified by X-ray absorption near-edge structure (XANES) and supported by density functional theory (DFT) calculation. This work provides a novel view to design highly effective and long-lasting rechargeable ZABs.

Energetic MOF-derived cobalt/iron nitrides embedded into N, S-codoped carbon nanotubes as superior bifunctional oxygen catalysts for Zn–air batteries

Exploring highly effcient bifunctional oxygen catalysts is a central issue for rechargeable Zn–air batteries. Herein, bimetallic cobalt/iron nitrides in situ embedded into nitrogen, sulfur-codoped carbon nanotubes (CoN/FeN@N,S-C-800) was firstly developed by pyrolysis of a Fe-glucosamine coated tetrazole energetic metal − organic framework. Due to the significant nitrogen (5.38at%) dopant content, the synergistic effect between bimetallic nitrides, and interconnected N, S-codoped carbon nanotubes, the as-prepared CoN/FeN@N,S-C-800 exhibits an ultra-high half-wave potential (0.865 V) for oxygen reduction reaction (ORR) and a low overpotential (385 mV) for oxygen evolution reaction (OER). The assembled liquid Zn–air battery affords a high peak power density of 168.3 mW cm−2 and a low voltage gap of 0.55 V after 600 cycles (100 h). Impressively, an all-solid-state ZAB catalyzed by CoN/FeN@N,S-C-800 affords a high OCV of 1.354 V, and three all-solid-state ZABs in series can successfully light LED (~2.2 V), displaying tremendous potentials in portable devices.

Synthesis of Ultrasmall NiCo2O4 Nanoparticle-Decorated N-Doped Graphene Nanosheets as an Effective Catalyst for Zn–Air Batteries

Synthesis of Ultrasmall NiCo₂O₄ Nanoparticle-Decorated N-Doped Graphene Nanosheets as an Effective Catalyst for Zn–Air Batteries

Enantioselective Vinylogous Mannich Reaction of Acyclic Vinylketene Silyl Acetals with Acyclic Ketimines

AbstractThe first enantioselective vinylogous Mannich reaction of acyclic vinylketene silyl acetals with acyclic ketimines derived from alkynyl ketoesters was developed. Excellent yields and enantioselectivities were obtained from the reaction using bis(imidazoline)‐Zn(II) catalyst. Based on experiments and MO calculation, a plausible transition state was proposed to explain the stereoselectivity of the reaction. The obtained products were converted into various amines and a lactam. This process provides an efficient route for the synthesis of acyclic δ‐amino‐α,β‐unsaturated carbonyl compounds and their derivatives.magnified image

Novel MOF-derived hollow CoFe alloy coupled with N-doped Ketjen Black as boosted bifunctional oxygen catalysts for Zn–air batteries

Rational design of highly effcient bifunctional oxygen catalysts toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is a significant challenge for rechargeable Zn–air battery (ZAB). Herein, a newly developed hybrid catalyst (denoted as CoFe@NC/KB-800) consisting of hollow CoFe alloy and nitrogen-doped Ketjen Black is synthesized by pyrolysis of a novel Fe-glucosamine coated cobalt-based metal–organic framework. By virtue of ultra-high specific surface area of 1318.8 m2 g−1 and micro-/meso-/macropore structure, the optimal CoFe@NC/KB-800 catalyst exhibits a low reversible oxygen overpotential (ΔE) of 0.77 V between ORR and OER. Density functional theory (DFT) calculations validate that the superior catalytic activity is ascribed to synergistic CoFe@NC structure. Impressively, liquid ZAB catalyzed by CoFe@NC/KB-800 displays a high peak power density of 160 mW cm−2 and a low voltage gap of 0.65 V after 600 cycles. Three all-solid-state ZABs in series can successfully light LED (~2.2 V), displaying tremendous potentials in portable devices.