https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/676 2026-07-03T23:14:29Z 2026-07-03T23:14:29Z Ahn, Su Min Lee, Seongho Lee, Ga-Been Natarajan, Logeshwaran Ravichandran, Balaji Kim, Nam Dong Kim, Sung-Soo Baek, Kitae Kang, Joonhee Yun, Hongseok Lee, Young Jun https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/211329 2026-03-18T02:30:29Z 2026-08-01T00:00:00Z

Title: Hydroxyl-blocking lignin-derived carbon catalysts for selective and durable hydrogen peroxide electrosynthesis Authors: Ahn, Su Min; Lee, Seongho; Lee, Ga-Been; Natarajan, Logeshwaran; Ravichandran, Balaji; Kim, Nam Dong; Kim, Sung-Soo; Baek, Kitae; Kang, Joonhee; Yun, Hongseok; Lee, Young Jun Abstract: Metal-free oxygen-functionalized carbon materials are promising electrocatalysts for selective hydrogen peroxide (H2O2) production via the two-electron oxygen reduction reaction (ORR). However, precisely controlling oxygen moieties while maintaining scalability remains challenging. Herein, we present a scalable and sustainable Friedel-Crafts reaction-assisted carbonization strategy that converts lignin into oxygen-tunable carbon catalysts for efficient H2O2 electrosynthesis. Electrochemical measurements reveal a strong correlation between carbonization temperature, oxygen speciation, and catalytic performance. Specifically, carbonyl and carboxyl groups enhance H2O2 selectivity, while hydroxyl groups suppress H2O2 formation by preferentially binding O* intermediates. Density functional theory corroborates these findings, indicating that carbonyl and carboxyl groups favor the two-electron pathway. Accordingly, selective blocking of hydroxyl groups achieves > 95 % H2O2 selectivity, a production rate of 575.5 mmol g(cat)(-1) h(-1) at 0.4 V-RHE, and stable operation for 40 h. This renewable, low-cost platform couples mechanistic control with scalable synthesis, potentially enabling decentralized H2O2 generation in on-site disinfection and wastewater treatment.

2026-08-01T00:00:00Z Parrey, Khursheed Ahmad Ayranci, Rukiye Choi, Hyosung Ak, Metin https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/217785 2026-07-02T02:30:22Z 2026-08-01T00:00:00Z

Title: Electrochemical Design of Reduced Graphene Oxide Supported Polyaniline-Metal Oxide Nanocomposites for Supercapacitor Applications Authors: Parrey, Khursheed Ahmad; Ayranci, Rukiye; Choi, Hyosung; Ak, Metin Abstract: Hybrid nanocomposites that integrate conducting polymers, metal oxides, and carbon frameworks offer a promising strategy for high-performance supercapacitor electrodes. In this work, reduced graphene oxide–supported polyaniline/metal oxide (ZnO, Fe2O3, and ZnFe2O4) nanocomposites were prepared and systematically investigated. The surface morphology, chemical composition, and structural and optical properties of the synthesized composites were systematically investigated using FE-SEM/EDX, AFM, UV–vis spectroscopy, and FTIR spectroscopy. Electrochemical performance was evaluated by cyclic voltammetry and electrochemical impedance spectroscopy, revealing typical pseudocapacitive behavior arising from synergistic faradaic contributions of PANI and metal oxides. Among the electrodes studied, rGO-supported PANI/ZnFe2O4 composite exhibited the best performance, delivering a competitive gravimetric specific capacitance of 294.13 F g−1, an energy density of 163.5 Wh kg−1, and a power density of 3658.5 W kg−1, along with a capacitance retention of about 81% after 2000 cycles at a scan rate of 50 mV/s. The superior performance is attributed to the combined effects of improved conductivity from rGO, enhanced redox activity from the bimetal oxide, and reduced charge-transfer resistance, as confirmed by impedance analysis. These results demonstrate the combined interaction among rGO, PANI, and metal oxide nanoparticles, highlighting rGO-supported PANI/metal oxide composites as a highly promising platform for the development of high-performance supercapacitor electrodes.

2026-08-01T00:00:00Z Yeo, Jeongmin Cho, Jaehyeon Jung, Je-Yeon Kim, Mi Song Kim, Kyungmi Park, Anseong Choi, Jeongi Kim, YongJoo Yang, Jung Hoon Lee, Won Bo Chae, Junghyun Chang, Jinho https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/213281 2026-06-16T04:30:30Z 2026-06-01T00:00:00Z

Title: Hydrophobic Solvation-Driven Stabilization of the Fluorenone Radical for the Anolyte of All-Organic Flow Batteries under Benign pH Conditions Authors: Yeo, Jeongmin; Cho, Jaehyeon; Jung, Je-Yeon; Kim, Mi Song; Kim, Kyungmi; Park, Anseong; Choi, Jeongi; Kim, YongJoo; Yang, Jung Hoon; Lee, Won Bo; Chae, Junghyun; Chang, Jinho Abstract: Fluorenone (FL) is a promising anolyte candidate for aqueous organic redox flow batteries (AORFBs), but its reduction is accompanied by protonation-induced degradation. Here, we demonstrated that the radical anion of fluorenone (FL–·) can be stabilized without alkalization by forming a hydrophobic solvation environment using highly concentrated 1-butyl-1-methylpyrrolidinium chloride (BMPyrCl). A water-soluble FL derivative enables systematic investigation of redox behavior across electrolyte conditions. Electrochemical and spectroscopic measurements and molecular dynamics simulations revealed that increasing BMPyrCl concentration induces a water-in-molecular-salt state, which expels water from the solvation shell of FL–· and suppresses its protonation, while the concentrated LiTFSI-based water-in-salt electrolyte cannot make the FL–· environment hydrophobic. When paired with a TEMPO-based catholyte, the resulting AORFB delivered stable cycling performance, with a significantly reduced capacity fade, and the cell achieved a voltage of 1.64 V, representing a notably high value for AORFBs employing organic electrolytes as both anolyte and catholyte. These results highlight that hydrophobic solvation design is a critical enabler of high-voltage, stable aqueous organic redox electrolyte-based energy storage systems.

2026-06-01T00:00:00Z Yoon, Saemon Lim, Han-Gyun Kim, Jinyoung Kim, Gyu Min Lee, Seojun Ryu, Jun Cho, Sungwon Kim, Jincheol Choi, Hyosung Cho, Jung Sang Park, Jongsung Kang, Dong-Won https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/213157 2026-07-01T02:30:39Z 2026-06-01T00:00:00Z

Title: In-Situ Solution Complexation for n-Type Surface-Energetics Reconstruction in 2.0 eV Ultra-Wide-Bandgap Perovskite Solar Cells Authors: Yoon, Saemon; Lim, Han-Gyun; Kim, Jinyoung; Kim, Gyu Min; Lee, Seojun; Ryu, Jun; Cho, Sungwon; Kim, Jincheol; Choi, Hyosung; Cho, Jung Sang; Park, Jongsung; Kang, Dong-Won Abstract: Ultra-wide-bandgap (UWBG) perovskites (>2.0 eV) are essential for high-efficiency triple-junction tandem solar cells but suffer from photo-induced phase segregation and open-circuit voltage (VOC) deficits arising from surface defects and energetic misalignment. Here, we report an in situ solution complexation (ISC) strategy to reconstruct the surface of 2.0 eV perovskites. By exploiting a proton transfer reaction between phenethylammonium chloride and ethylenediamine, we activate the passivation agents to selectively deplete unstable surface iodine clusters and eliminate metallic lead defects. This chemical reconstruction induces a degenerate-like n-type surface with pronounced downward band bending, simultaneously forming a robust hole-blocking barrier and enabling efficient electron extraction via an Ohmic tunneling contact. Consequently, the ISC-treated 2.0 eV single-junction device achieves a power conversion efficiency (PCE) of 15.7% with a high VOC of 1.41 V and a fill factor of 0.84, while exhibiting superior photostability by suppressing phase segregation. Leveraging this UWBG top cell together with a 1.5 eV perovskite bottom cell, we further demonstrate a monolithic all-perovskite tandem solar cell delivering a PCE of 24.2% with a VOC of 2.58 V. This work provides a practical pathway to minimize voltage losses and stabilize UWBG perovskites, advancing perovskite tandems toward perovskite/perovskite/Si triple-junction architecture.

2026-06-01T00:00:00Z