Making an ultralow platinum content bimetallic catalyst on carbon fibres for electro-oxidation of ammonia in wastewater

Abstract

Electrocatalysis of wastewater containing ammonia is a promising alternative to chemical and biological water purification for several reasons, one being that energy-rich hydrogen gas is generated as a byproduct while the reaction can be strictly controlled to meet demands. An objective has been to reduce the loading of expensive platinum (Pt) in the catalyst electrodes, and to reduce the poisoning of the metal surface during the electrolysis. Herein, the co-deposition of a copper-platinum (Cu-Pt) bimetallic alloy onto carbon filaments, stripped from their polymeric coating, is shown to give an electrocatalytic performance superior to that of pure Pt at a content of less than 3 wt% Pt. The key to the enhanced performance was to take advantage of micrometer-sized carbon filaments to distribute a very large bimetallic alloy surface uniformly over the filaments. The Cu-Pt-alloy-coated filaments also suffer less electrode poisoning than pure Pt, and are bonded more strongly to the carbon fibre due to better mechanical interlocking between the bimetallic alloy and the carbon filaments. High-resolution electron microscopy studies combined with a tuned electro-deposition process made it possible to tailor the catalyst micro/nano morphology to reach a uniform coverage, surrounding the entire carbon filaments.The results are promising steps towards large-scale wastewater treatment, combined with clean energy production from regenerated hydrogen.Fig. 7 SEM images of potentiostatic electrodeposited carbon fibres with layers of a binary alloy of copper-platinum after 2 h (a, b, d, and e); (c) low magnification of the galvanostatic electrodeposition mode; (f and g) low and high magnifications of the carbon fibre/deposit interface; (h) SEM-EDX element mapping of À0.2 V electrodeposited sample for carbon (C), oxygen (O), copper (Cu), and platinum (Pt) elements.

Ternary PtIrNi Catalysts for Efficient Electrochemical Ammonia Oxidation

“…As expected, the onset potentials of AOR on all of these Pt catalysts are very high, around 0.5 V vs RHE, according to Figures 6a,b, S12a, and S13, which is insufficient for a DAFC. Previous reports had demonstrated that incorporation of Ir into Pt is a promising strategy for negatively shifting the onset potential of the AOR with reduced overpotentials, 19,25,26 likely due to the bifunctional mechanism and the electronic effect, as discussed above. 30,54 6c and Table S3).…”

“…As expected, the onset potentials of AOR on all of these Pt catalysts are very high, around 0.5 V vs RHE, according to Figures a,b, S12a, and S13, which is insufficient for a DAFC. Previous reports had demonstrated that incorporation of Ir into Pt is a promising strategy for negatively shifting the onset potential of the AOR with reduced overpotentials, ,, likely due to the bifunctional mechanism and the electronic effect, as discussed above. , For a step-by-step study of the promotional role of Ir and Ni in improving AOR activity, we first introduced secondary metals Ir or Ni at a molar ratio of 9:1 in Pt catalysts. Improved activity of both PtIr/SiO 2 -CNT-COOH and PtNi/SiO 2 -CNT-COOH compared to Pt/SiO 2 -CNT-COOH and commercial Pt/C was demonstrated (Figure c and Table S3).…”

“…To this end, the development of Pt–Ir alloy catalysts has attracted greater research interest compared to other alloys ( e.g. , Pt–Ni, Pt–Rh, and Pt–Cu). ,,,− The enhanced AOR activity of the Pt–Ir alloys has been previously reported, ,, which has been regarded as the baseline for AOR studies …”

Highly Permeable Fluorinated Polymer Nanocomposites for Plasmonic Hydrogen Sensing

“…Hydrogen gas (H 2 ) is an efficient carbon-free energy carrier that can be extracted from sources that include natural gas, biomass, or water/wastewater. , In contrast to the combustion of fossil fuels, the conversion of H 2 to electrical energy in a fuel cell produces only water, without any CO 2 emissions . Therefore, a transition from carbon-based fuels to H 2 could ultimately play a key role in mitigating climate change .…”

Application of Waste Polymers as Basic Material for Ultrafiltration Membranes Preparation

“…Removal of ammonia values was 25.5% and 84.0%, respectively. Ultrafiltration process can be also combined with other processes like electrocatalysis or electrooxidation for removal of the smallest substances: ammonia and salts [42,43].…”