Green and renewable energy technologies, such as fuel cells, batteries, and water-splitting, hold great promise to solve current energy and environmental challenges. However, noble metal catalysts (e.g., Pt, Ru, Ir, Pd) are generally needed to promote the hydrogen evolution reaction (HER) for hydrogen fuel generation from photo-electrochemical water-splitting, oxygen reduction reaction (ORR) in fuel cells for energy conversion, and oxygen evolution reaction (OER) in metal-air batteries for energy storage. The high cost of precious metal-based catalysts and their limited reserve have precluded these renewable energy technologies from large-scale applications. Along with the recent intensive research efforts in reducing or replacing noble metal based catalysts (i.e., Pt) for ORR in fuel cells, we have previously demonstrated that vertically aligned nitrogen-doped carbon nanotubes (VA-NCNTs) could actively catalyze ORR via a four-electron process free from the methanol crossover and CO poisoning effects with a 3-time higher electrocatalytic activity and better long-term durability than that of commercially available Pt/C catalysts. The improved catalytic performance was attributed to the doping-induced charge transfer from adjacent carbon atoms to the nitrogen atoms to change the chemisorption mode of O2 and to readily attract electrons from the anode for facilitating the ORR. Subsequently, various carbon nanomaterials, mono-/co-/tri-doped with heteroatoms of different electronegativities from that of carbon, physically adsorbed with certain polyelectrolytes, and even without any apparent dopant or physically adsorbed polyelectrolyte, could also exhibit good ORR performance caused by intermolecular charge-transfer with the adsorbed polyelectrolytes or defect-induced charge redistribution. More recent studies have further demonstrated that heteroatom-doped carbon nanomaterials can act as metal-free bifunctional catalysts for ORR or OER and HER for self-powered water-splitting to generate hydrogen fuel and oxygen gas from water, ORR and OER in metal-air batteries for energy storage, and even ORR/OER/HER trifunctional catalysis for integrated energy systems. In this talk, we will summarize some of our work on the metal-free catalysts based on carbon nanomaterials for various energy-related reactions, along with an overview on the recent advances and perspectives in this exciting field.

Multifunctional carbon-based metal-free catalysts for efficient energy conversion and storage

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.