Engineering of nanostructured metal-based catalysts for electrochemical reduction of CO2

Electrochemical carbon dioxide reduction (ECO2R) into value-added chemicals and liquid fuels using renewable energy is considered as a viable option for CO2 recycling and closing the carbon cycle. Design and development of cheap and efficient catalysts holds the key to the practical implementation of this technology. Studies have focused on the development of nanostructured metal-based catalysts for ECO2R. The interfacial and surface engineering are two efficient strategies to improve the catalytic properties of these metal-based catalysts by altering the intrinsic activity and the electronic structure of the catalysts. This thesis focuses on the utilization of these two strategies to tune catalysts for achieving improved ECO2R performance. Three different nanostructured metal-based catalysts have been developed via simple and scalable methods including core-shell structured gold-polyaniline (Au-PANI) nanocomposites, nitrogen-doped carbon supported copper nanoparticles and copper oxide-derived copper nanowires

Scalable Solution Processing MoS2 Powders with Liquid Crystalline Graphene Oxide for Flexible Freestanding Films with High Areal Lithium Storage Capacity

2019 American Chemical Society. Freestanding flexible electrodes with high areal mass loading are required for the development of flexible high-performance lithium-ion batteries (LIBs). Currently they face the challenge of low mass loading due to the limited concentrations attainable in processable dispersions. Here, we report a simple low-temperature hydrothermal route to fabricate flexible layered molybdenum disulfide (MoS2)/reduced graphene oxide (MSG) films offering high areal capacity and good lithium storage performance. This is achieved using a self-assembly process facilitated by the use of liquid crystalline graphene oxide (LCGO) and commercial MoS2 powders at a low temperature of 70 °C. The amphiphilic properties of ultralarge LCGO nanosheets facilitates the processability of large-size MoS2 powders, which is otherwise nondispersible in water. The resultant film with an areal mass of 8.2 mg cm-2 delivers a high areal capacity of 5.80 mAh cm-2 (706 mAh g-1) at 0.1 A g-1. This simple method can be adapted to similar nondispersible commercial battery materials for films fabrication or production of more complicated constructs via advanced fabrication technologies

A Self‐Assembled CO2 Reduction Electrocatalyst: Posy‐Bouquet‐Shaped Gold‐Polyaniline Core‐Shell Nanocomposite

© 2020 Wiley-VCH GmbH Here it was demonstrated that the decoration of gold (Au) with polyaniline is an effective approach in increasing its electrocatalytic reduction of CO2 to CO. The core-shell-structured gold-polyaniline (Au−PANI) nanocomposite delivered a CO2-to-CO conversion efficiency of 85 % with a high current density of 11.6 mA cm−2. The polyaniline shell facilitated CO2 adsorption, and the subsequent formation of reaction intermediates on the gold core contributed to the high efficiency observed

Tuning the structure of three dimensional nanostructured molybdenum disulfide/nitrogen-doped carbon composite for high lithium storage

Molybdenum disulfide/nitrogen-doped carbon nanocomposite can afford high capacity, good rate capability and cycling stability in lithium ion batteries owing to the synergistic effect from these two components. Structure of the material has a great impact on the performance as well. In this work, MoS2/nitrogen-doped carbon (MoS2/C) composites have been developed by manipulating the nano-featured polypyrrole templates to guide and confine their growth. They are formed via a simple hydrothermal process combined with a subsequent annealing process. The MoS2/nitrogen-doped carbon nanotubes (MoS2/CNT) composite with 76% of MoS2 exhibits an excellent performance including a high capacity of 1232 mAh g−1 at a current density of 0.1 A g−1, outstanding rate capability (947 mAh g−1 at 2 A g−1), and good cycling stability with 754 mAh g−1 retained over 1000 charge/discharge cycles at a high current density of 1 A g−1. This performance is much better than that MoS2/nitrogen-doped carbon nanoparticles (MoS2/CNP) composite. This work demonstrates the importance of introducing three-dimensional nanostructures in electrode materials to improve their electrochemical performance

A Nitrogen-Doped Porous Carbon Supported Copper Catalyst from a Scalable One-Step Method for Efficient Carbon Dioxide Electroreduction

In this work, a scalable one-step glucose blowing method has been used to prepare a porous N-doped carbon supported Cu nanoparticles (Cu-NC) composite catalyst for CO2 electroreduction. This Cu-NC catalyst demonstrates efficient catalytic activity for CO2-to-C1 product (CO and formate) conversion, with a high efficiency of 69 % at an overpotential of 590 mV. The excellent catalytic activity is correlated to the structure of this composite and the N-species (pyridinic and graphitic nitrogen) in the carbonaceous matrix that may promote the CO2 adsorption and subsequent formation of reduction reaction intermediates and products

A versatile transition metal ion-binding motif derived from covalent organic framework for efficient CO\u3csub\u3e2\u3c/sub\u3e electroreduction

We demonstrate a versatile transition metal ion-binding motif for constructing highly efficient metal atom-embedded carbon catalysts for electrochemical CO production. It is a mesoporous N-doped carbon (N-C) derived from a covalent organic framework via molten-salt assisted carbonization. Three different transition metals (Co, Fe or Ni) have been immobilized into the N-rich mesopores via ion coordination, forming catalysts with isolated and coordinately unsaturated metal-N moieties. These catalysts all exhibit excellent electrocatalytic activities for CO -to-CO conversion with a high faradaic efficiency \u3e 80 % and a high current density \u3e 10 mA cm at modest overpotentials around 500 mV. Using Ni- or Fe-N-C, a highly selective (\u3e 95 %) CO generation was observed. By performing the structure-property analysis with three other N-C materials as control, such high performance is ascribed to the efficient metal-N catalytic sites generated by the cooperative immobilization of metal atoms with pyridinic-N and pyrrolic-N species in the mesoporous carbon matrix. 2 −

A Self‐Assembled CO 2

© 2020 Wiley-VCH GmbH Here it was demonstrated that the decoration of gold (Au) with polyaniline is an effective approach in increasing its electrocatalytic reduction of CO2 to CO. The core-shell-structured gold-polyaniline (Au−PANI) nanocomposite delivered a CO2-to-CO conversion efficiency of 85 % with a high current density of 11.6 mA cm−2. The polyaniline shell facilitated CO2 adsorption, and the subsequent formation of reaction intermediates on the gold core contributed to the high efficiency observed

Hierarchical architectures of mesoporous Pd on highly ordered TiO2 nanotube arrays for electrochemical CO2 reduction

This journal is © The Royal Society of Chemistry. The understanding of the influence of hierarchically nanostructured architectures as support materials for catalysts loading, is critical towards development of efficient electrocatalytic interfaces. The knowledge on mass transport limitation of reactants within such catalyst-support structures remains elusive. Herein, we performed systematic investigation through a novel hierarchical 1D-3D structure by loading mesoporous Pd with an average pore size of ∼10 nm and wall thickness of ∼4 nm onto highly ordered TiO2 nanotube arrays via pulse electrodeposition. Electrochemical CO2 reductions achieved a CO2-to-formate faradaic conversion efficiency of 88 ± 2% under optimal conditions. Importantly, the product selectivity is found to depend significantly on the tube length, highlighting the influence of mass transport limitations of CO2. This work offers vital insight into practical consideration in designing efficient catalyst-support interfaces with an optimal hierarchically geometry, that must optimise mass transport as well as electrochemical kinetics