Electrochemical Oxygen Reduction Reaction Performance of Water Hyacinth Derived Porous Non-precious Electrocatalyst in Alkaline Media

¹ Faculty of Science, Energy and Environment, King Mongkut’s University of Technology North Bangkok, Rayong Campus, Rayong, Thailand
² Faculty of Engineering and Technology, King Mongkut’s University of Technology North Bangkok, Rayong Campus, Rayong, Thailand
³ Automotive Eco-Energy and Industrial Product Standard Research Center, Science and Technology Research Institute, King Mongkut’s University of Technology North Bangkok, Rayong, Thailand
⁴ College of Industrial Technology, King Mongkut’s University of Technology North Bangkok, Bangkok, Thailand
⁵ Integrated Nanoscience Research Center, Science and Technology Research Institute, King Mongkut’s University of Technology North Bangkok, Bangkok, Thailand
⁶ Department of Industrial Chemistry, Faculty of Applied Science, King Mongkut’s University of Technology North Bangkok, Bangkok, Thailand

^* Corresponding author: kriangsak.k@sciee.kmutnb.ac.th

Abstract

This research studied the possibility of converting water hyacinth biomass into the porous non-precious oxygen reduction reaction (ORR) electrocatalyst using a simple, low cost and scalable autogenic pressure method. The electrocatalyst was prepared by thermally annealing water hyacinth root contained ZnCl2 at 700^oC under autogenic pressure conditions. The phase of the catalyst was the mixture of carbon and metal oxide. In addition, rough surface morphology and high porosity were clearly observed using scanning electron microscope. The synthesized catalyst was then determined the ORR performance by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) techniques under O2 saturated KOH solution. The ORR performance increased as the catalyst loading was increased and the optimum catalyst loading was found to be 1.5 mg/cm² which generated the Eonset and E1/2 value of 0.93 V and 0.80 V vs. RHE, respectively. Furthermore, the E1/2 value of the synthesized catalyst was 230 and 130 mV greater than the catalyst synthesized without ZnCl2 and commercial carbon (VXC-72R). ORR durability study suggested that the prepared catalyst was durable to operate ORR for 5000 cycles in alkaline media. These results suggested that the autogenic pressure conditions would be a promising technique to prepare highly active and durable biomass derived ORR electrocatalyst.