Long-lasting BDD/Si₃N₄-TiN electrodes for sustainable water remediation

resumo

Boron-doped diamond (BDD) thin films have the potential to revolutionize water remediation through electrochemical oxidation, converting persistent pollutants into CO2 and water. However, a significant challenge in implementing BDDs on a large scale is the choice of substrate material. Electrode failure typically occurs due to BDD delamination from the substrate. We propose using a ceramic composite of silicon nitride (Si3N4) and titanium nitride (TiN) as a substrate to address this issue. This electroconductive composite combines Si3N4's high wear resistance, chemical stability, and high affinity for diamond film growth with the TiN's metal-like conductivity. In this work, BDD films were grown by Hot Filament Chemical Vapor Deposition (HF-CVD) over Si3N4-TiN substrates containing 30%vol. TiN. The resulting BDD/Si3N4-TiN electrodes were analyzed concerning their microstructure, diamond quality, conductivity, adhesion strength, service life, and electrochemical properties. Phenol was used as a model to test the electrode's ability to oxidize pollutants. We found that the BDD/Si3N4-TiN electrode could eliminate phenol entirely and up to 98.8 % of the model solution's Chemical Oxygen Demand (COD) after 5 h of direct anodic oxidation, with an Average Current Efficiency (ACE) of 14 % and an energy consumption of 138 kW h kgCOD1. Furthermore, the BDD/Si3N4-TiN electrode could withstand more than 2016 h of accelerated life test without film delamination. Overall, the results demonstrate that BDD/Si3N4-TiN electrodes are a potential long-lasting solution for large-scale water treatment by electrochemical advanced oxidation processes (EAOPs) in a sustainable manner, especially if combined with renewable energy sources.

palavras-chave

BORON-DOPED DIAMOND; ENHANCED ELECTROCHEMICAL OXIDATION; P-SUBSTITUTED PHENOLS; WASTE-WATER; SILICON-NITRIDE; ANODIC-OXIDATION; HIGH-PERFORMANCE; RAMAN-SPECTROSCOPY; COATED TITANIUM; AQUEOUS PHENOL

categoria

Materials Science

autores

Brosler, P; Sousa, I; Nadais, HGD; Silva, RFE; Tedim, J; Oliveira, FJ

Grupos

G3 - Materiais Eletroquímicos, Interfaces e Revestimentos

Projectos

CICECO - Aveiro Institute of Materials (UIDB/50011/2020)

CICECO - Aveiro Institute of Materials (UIDP/50011/2020)

Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)

Collaboratory for Emerging Technologies, CoLab (EMERGING TECHNOLOGIES)

agradecimentos

This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MEC (PIDDAC) . This work was also developed within CESAM-Centre for Environmental and Marine Studies & Department of Environment and Planning (UIDP/50017/2020 + UIDB/50017/2020) , financed by na-tional funds through FCT/MCTES. This work is also funded by national funds (OE) through FCT - Fundacao para a Ciencia e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19.