Innovative Electrode Nanocomposites for Energy Storage and Conversion Systems

Nanocomposites emerged as suitable alternatives for electrode materials, are defined as “two or more materials with different properties remain separate and distinct on a macroscopic level within one unity and with any dimension in any phase less than 100 nm”. Recently, polymer/carbon based nanocomposites have attracted significant research interests for energy applications due to their multi-functionalities, improved structure stability and ease of production. This dissertation work focusing on the development of innovative electrode nanocomposites for proton exchange membrane fuel cell, supercapacitor and electrochromic applications.

Chapter 1 is an introduction. Chapter 2 & 3 focus on the synthesis of Pd-based nanocatalysts for EOR [ethanol oxidation reaction]. The effect of Pd loading in Pd/MWNTs [multi-walled carbon nanotubes], the conversion of Pd precursor and the variation of functionalized carboxylic groups on tube wall surface have been investigated through varying precursor ratios. A follow-up work focusing on integrating E [oxyphilic metal] and MO [metal oxides] into Pd/MWNTs nanocatalysts proceeds in Chapter 3. Ultrafine FePd nanoalloys deposited on γ-Fe₂O₃ [gamma iron oxides], FePd-Fe₂O₃, anchored on MWNTs, FePd-Fe₂O₃/MWNTs, have been successfully synthesized for EOR. A 3.65 fold increase of peak current density compared with that of Pd/MWNTs was observed in cyclic voltammetry after normalizing to Pd mass. Chapter 4 & 5 focus on the synthesis of electrode nanocomposites for supercapacitor and electrochromic applications, hybrid PANI [polyaniline] and MnFe₂O₄ [manganese iron oxide] nanocomposites film has been successfully synthesized for combined electrochromic and energy storage applications. The synthesized hybrid film exhibited enhanced electrochromic and energy storage performances compared to pristine PANI film due to the synergistic effect between the nanofillers and PANI matrix, nanofiller resulted porous structure of PANI and energy storage contribution of MnFe₂O₄. Chapter 5 presents a facile hydrothermal method to enhance the energy storage property of graphene by employing KOH activation and N-doping processes. The synthesized graphene exhibited largely enhanced capacitance (186.63 F/g) and cycling stability compared with that of N-G [nitrogen doped graphene, 50.88 F/g] and AG [activated graphene, 58.38 F/g] due to the increased defects on graphene sheet and the introduced active N defects. Conclusions and future work are provided in Chapter 6.