https://scholar.dgist.ac.kr/handle/20.500.11750/237 2026-08-03T13:38:50Z https://scholar.dgist.ac.kr/handle/20.500.11750/60543 Title: Efficient Electrochemical NO Reduction at Low Overpotential via Synergistic RuCu Alloy Nanoparticles Author(s): Jang, Seoyoung; Joo, Yong Lak; Shanmugam, Sangaraju Abstract: Ammonia (NH3) synthesis via electrochemical nitric oxide reduction (NORR) has emerged as a promising alternative to the Haber-Bosch process, which requires high temperatures and pressures. However, NORR still faces critical challenges, including side reactions, limited mass transfer, and high overpotential requirements. Transition metals have been widely employed to address these issues owing to their favorable NO adsorption properties; however, they suffer from intermediate overbinding and require high overpotentials to achieve meaningful catalytic activity. To overcome these limitations, we introduce a noble-metal alloying strategy that combines the high electron-transfer kinetics of noble metals with the tunable NO adsorption properties of transition metals, thereby synergistically enhancing catalytic activity for selective NH3 production. We designed Ru-Cu alloy nanoparticles supported on nitrogen-doped carbon nanorods (Ru x Cu100-x @NCNR), and the optimized Ru5Cu95@NCNR catalyst exhibited an ammonia yield of 32.66 +/- 4.38 mu mol cm-2 h-1 and a Faradaic efficiency of 94 +/- 1.25% (FENH3) at -0.2 V vs RHE, notably lower overpotential than that reported for conventional NORR catalysts, demonstrating energy-efficient ammonia production. Long-term stability tests confirmed the sustained catalytic performance, and its practical applicability was further validated through integration into a Zn-NO battery system, highlighting its potential for next-generation energy conversion devices. Mechanistic investigations revealed that precise control of Ru content induces structural modulation of the RuCu alloy, thereby regulating the strength of NO adsorption and facilitating efficient protonation, ultimately governing high NH3 selectivity. 2026-05-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60539 Title: Stabilizing Highly Sulfonated Poly(ether ether ketone) Membranes with Polybenzimidazole for Zinc-Bromine Redox Flow Batteries Author(s): Jannah, Sifathul; Kim, Minji; Shanmugam, Sangaraju Abstract: Zinc-bromine redox flow batteries (ZBRFBs) suffer from membrane degradation under bromine-rich operating conditions. Highly sulfonated poly(ether ether ketone) (SPEEK) at DS approximate to 75-79% offers superior ionic conductivity but undergoes excessive swelling and mechanical failure in ZBRFB electrolytes. Here, we report the first systematic application of Na+-pretreated SPEEK/polybenzimidazole (PBI) blend membranes to ZBRFBs, where Na+-ion exchange pretreatment enables homogeneous blending of these otherwise incompatible polymers. The optimized SPEEK/PBI 2.5 wt % membrane achieves a 3-fold reduction in Br-2 permeability and improves energy efficiency from 83.6% to 88.4%, retaining 94.22% discharge capacity after 280 cycles versus 54% at failure for pristine SPEEK at cycle 85. Postmortem analysis confirms reduced desulfonation and improved morphological integrity, consistent with the acid-base network reinforcement by PBI. These results demonstrate that controlled PBI blending effectively extends the usable DS range of SPEEK in harsh bromine-containing electrolytes. 2026-04-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60000 Title: Cationic Covalent Organic Framework-Based Membranes for High-Performance Zn/Br2 Redox Flow Batteries Author(s): Han, Dabin; Abuawwad, Lamia; Kim, Minji; Schneemann, Andreas; Shanmugam, Sangaraju Abstract: Zn/Br2 redox flow batteries (Zn/Br2 RFBs) have attracted significant attention for large-scale energy storage applications due to their high safety and efficiency. The membrane is a critical component of Zn/Br2 RFBs, directly influencing their efficiency and power density. However, designing suitable membranes is challenging due to an intrinsic trade-off between achieving fast bi-ionic species transport (Zn2+ and Br−). Increasing anion transport pathways improves Br− conductivity but simultaneously accelerates Brn− shuttling and self-discharge, while strong Brn− blocking typically restricts anion mobility and causes ionic imbalance. To address this trade-off, a membrane design strategy is proposed that enhances anion conduction while simultaneously suppressing Brn− migration by incorporating a cationic COF construced from ethidium bromide and triformylphloroglucinol (EB-COF) into a Nafion (NF) matrix. The EB-COF exhibits -CHO and -NH2 functional groups on its surface. The interaction between water molecules and these functional groups forms continuous, abundant water networks within the composite membrane, significantly enhancing its ion conductivity. In addition, the abundant quaternary amine groups (N+) of the EB-COF significantly reduce the polybromide (Brn−) shuttle by absorbing Br2 while forming Brn−. In particular, NF/EB-COF(0.3), in which 0.3 wt.% EB-COF is introduced into the NF polymer matrix, exhibits the most effective characteristics and has excellent performance for Zn/Br2 RFBs. Consequently, the Zn/Br2 RFBs assembled with the NF/EB-COF composite membrane demonstrate outstanding performance, achieving an energy efficiency of 89.1% at a current density of 40 mA cm−2. 2026-01-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59979 Title: Single Atom Catalysts for Electrochemical CO2 Reduction Reaction: Synthetic Strategies and Mechanistic Insights Author(s): Zafar, Anum; Shanmugam, Sangaraju; Zhang, Xinyi Abstract: Electrocatalytic CO2 reduction is one of the most promising pathways for addressing environmental and green energy concerns while converting CO2 into added value chemicals and fuels. For this purpose, single-atom catalysts (SACs) have emerged as highly active and selective classes of materials toward electrochemical CO2 reduction (CO2RR) due to their unique electronic properties, exposed active centers, and tunable coordination environment. Herein, a critical assessment of the recent development of SACs for CO2RR is presented. Rational design and synthetic strategies of SACs have been summarized. The interaction of ligands and modulation of both activity and selectivity with extensive analysis on local atomic structure and different SAC types is discussed. The reaction mechanisms of SACs based CO2RR and synergistic effect of SACs with nanoparticles and nanoclusters are also highlighted, emphasizing enhanced catalytic performance due to improved charge transfer, optimized binding of intermediates, and improved accessibility of the active site. Finally, the future perspective of SACs based CO2RR is provided. 2025-08-31T15:00:00Z