1. Self-adaptive amorphous ▫$CoO_xCl_y$▫ electrocatalyst for sustainable chlorine evolution in acidic brineMengjun Xiao, Qianbao Wu, Ruiqi Ku, Liujiang Zhou, Chang Long, Junwu Liang, Andraž Mavrič, Lei Li, Jing Zhu, Matjaž Valant, 2023, original scientific article Abstract: Electrochemical chlorine evolution reaction is of central importance in the chlor-alkali industry, but the chlorine evolution anode is largely limited by water oxidation side reaction and corrosion-induced performance decay in strong acids. Here we present an amorphous CoOxCly catalyst that has been deposited in situ in an acidic saline electrolyte containing Co2+ and Cl- ions to adapt to the given electrochemical condition and exhibits ~100% chlorine evolution selectivity with an overpotential of ~0.1 V at 10 mA cm−2 and high stability over 500 h. In situ spectroscopic studies and theoretical calculations reveal that the electrochemical introduction of Cl- prevents the Co sites from charging to a higher oxidation state thus suppressing the O-O bond formation for oxygen evolution. Consequently, the chlorine evolution selectivity has been enhanced on the Cl-constrained Co-O* sites via the Volmer-Heyrovsky pathway. This study provides fundamental insights into how the reactant Cl-itself can work as a promoter toward enhancing chlorine evolution in acidic brine. Keywords: catalyst synthesis, electrocatalysis, chlorine evolution Published in RUNG: 04.09.2023; Views: 2066; Downloads: 8 Full text (3,05 MB) This document has many files! More... |
2. Non-covalent ligand-oxide interaction promotes oxygen evolutionQianbao Wu, Junwu Liang, Mengjun Xiao, Chang Long, Lei Li, Zhenhua Zeng, Andraž Mavrič, Xia Zheng, Jing Zhu, Matjaž Valant, 2023, original scientific article Abstract: Strategies to generate high-valence metal species capable of oxidizing water often employ composition and coordination tuning of oxide-based catalysts, where strong covalent interactions with metal sites are crucial. However, it remains unexplored whether a relatively weak “non-bonding” interaction between ligands and oxides can mediate the electronic states of metal sites in oxides. Here we present an unusual non-covalent phenanthroline-CoO2 interaction that substantially elevates the population of Co4+ sites for improved water oxidation. We find that phenanthroline only coordinates with Co2+ forming soluble Co(phenanthroline)2(OH)2 complex in alkaline electrolytes, which can be deposited as amorphous CoOxHy film containing non-bonding phenanthroline upon oxidation of Co2+ to Co3+/4+. This in situ deposited catalyst demonstrates a low overpotential of 216 mV at 10 mA cm−2 and sustainable activity over 1600 h with Faradaic efficiency above 97%. Density functional theory calculations reveal that the presence of phenanthroline can stabilize CoO2 through the non-covalent interaction and generate polaron-like electronic states at the Co-Co center. Keywords: water oxidation, cobalt hydroxide, ligand-metal interactions Published in RUNG: 23.02.2023; Views: 2413; Downloads: 19 Full text (1,77 MB) |
3. Biofunctionalized AlGaN/GaN high electron mobility transistor for DNA hybridization detectionResham Thapa, Siddharth Alur, Kyusang Kim, Fei Tong, Yogesh Sharma, Moonil Kim, Claude Ahyi, Jing Dai, Jong Wook Hong, Michael Bozack, John Williams, Ahjeong Son, Amir Dabiran, Minseo Park, 2012, original scientific article Keywords: AlGaN/GaN HEMT, DNA hybridization detection Published in RUNG: 16.01.2017; Views: 5434; Downloads: 0 This document has many files! More... |