Luis Estevez

Self-Assembled Fe-N-Doped Carbon Nanotube Aerogels with Single-Atom Catalyst Feature as High-Efficiency Oxygen Reduction Electrocatalysts

Self-assembled M-N-doped carbon nanotube aerogels with single-atom catalyst feature are for the first time reported through one-step hydrothermal route and subsequent facile annealing treatment. By taking advantage of the porous nanostructures, 1D nanotubes as well as single-atom catalyst feature, the resultant Fe-N-doped carbon nanotube aerogels exhibit excellent oxygen reduction reaction electrocatalytic performance even better than commercial Pt/C in alkaline solution.

Tunable Oxygen Functional Groups as Electrocatalysts on Graphite Felt Surfaces for All‐Vanadium Flow Batteries

A dual oxidative approach using O2 plasma followed by treatment with H2 O2 to impart oxygen functional groups onto the surface of a graphite felt electrode. When used as electrodes for an all-vanadium redox flow battery (VRB) system, the energy efficiency of the cell is enhanced by 8.2 % at a current density of 150 mA cm(-2) compared with one oxidized by thermal treatment in air. More importantly, by varying the oxidative techniques, the amount and type of oxygen groups was tailored and their effects were elucidated. It was found that O-C=O groups improve the cells performance whereas the C-O and C=O groups degrade it. The reason for the increased performance was found to be a reduction in the cell overpotential after functionalization of the graphite felt electrode. This work reveals a route for functionalizing carbon electrodes to improve the performance of VRB cells. This approach can lower the cost of VRB cells and pave the way for more commercially viable stationary energy storage systems that can be used for intermittent renewable energy storage.

Hierarchically Porous Graphitic Carbon with Simultaneously High Surface Area and Colossal Pore Volume Engineered via Ice Templating

Developing hierarchical porous carbon (HPC) materials with competing textural characteristics such as surface area and pore volume in one material is difficult to accomplish, particularly for an atomically ordered graphitic carbon. Herein we describe a synthesis strategy to engineer tunable HPC materials across micro-, meso-, and macroporous length scales, allowing the fabrication of a graphitic HPC material (HPC-G) with both very high surface area (>2500 m2/g) and pore volume (>11 cm3/g), the combination of which has not been attained previously. The mesopore volume alone for these materials is up to 7.53 cm3/g, the highest ever reported, higher than even any porous carbons total pore volume, which for our HPC-G material was >11 cm3/g. This HPC-G material was explored for use both as a supercapacitor electrode and for oil adsorption, two applications that require either high surface area or large pore volume, textural properties that are typically exclusive to one another. We accomplished these high textural characteristics by employing ice templating not only as a route for macroporous formation but as a synergistic vehicle that enabled the significant loading of the mesoporous hard template. This design scheme for HPC-G materials can be utilized in broad applications, including electrochemical systems such as batteries and supercapacitors, sorbents, and catalyst supports, particularly supports where a high degree of thermal stability is required.