https://scholar.dgist.ac.kr/handle/20.500.11750/12080 Sat, 04 Apr 2026 14:43:23 GMT 2026-04-04T14:43:23Z https://scholar.dgist.ac.kr/handle/20.500.11750/58600 Title: Advancements in Understanding Catalyst Reconstruction During Electrochemical CO2 Reduction Author(s): Kwon, Woosuck; Kim, Dohun; Lee, Yujin; Jung, Jinoh; Nam, Dae-Hyun Abstract: Electrochemical CO2 reduction reaction (CO2RR) has received great attention to solve CO2- induced global warming and carbon neutrality. It is essential to enhance the electrochemical CO2RR selectivity, activity, and long-term stability for sustainable manufacturing of specific chemicals via CO2RR. To produce multi-carbon (C2+) chemicals, Cu-based heterogeneous catalysts have been developed in terms of defect engineering, morphological design, and facet control. Despite the substantial efforts for the design of efficient Cu-based heterogeneous catalysts, there exist inevitable structural changes of catalysts with continuous dissolution and redeposition during CO2RR. This reconstruction modifies the as-synthesized catalysts into an unpredictable structure and leads to changes in active site. Here, we review the reconstruction of Cu-based catalysts during CO2RR, which occurs via continuous dissolution and redeposition process. This includes fundamental principles of reconstruction and the effect of microenvironment on reconstruction during CO2RR. We offer research progress about the reconstruction of Cu-based electrocatalysts, analysis methodologies to track the reconstruction, and the insight to improve the activity, selectivity, and stability of CO2RR. We provide perspective to understand and harness the reconstruction for the development of efficient CO2RR catalysts. Thu, 31 Jul 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/58600 2025-07-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/57430 Title: Thermodynamic phase control of Cu-Sn alloy electrocatalysts for selective CO2 reduction Author(s): Go, Soohyun; Kwon, Woosuck; Hong, Deokgi; Lee, Taemin; Oh, Sang-Ho; Bae, Daewon; Kim, Jeong-Heon; Lim, Seolha; Joo, Young-Chang; Nam, Dae-Hyun Abstract: In the electrochemical CO2 reduction reaction (CO2RR), Cu alloy electrocatalysts can control the CO2RR selectivity by modulating the intermediate binding energy. Here, we report the thermodynamic-based Cu-Sn bimetallic phase control in heterogeneous catalysts for selective CO2 conversion. Starting from the thermodynamic understanding about Cu-Sn bimetallic compounds, we established the specific processing window for Cu-Sn bimetallic phase control. To modulate the Cu-Sn bimetallic phases, we controlled the oxygen partial pressure (pO2) during the calcination of electrospun Cu and Sn ions-incorporated nanofibers (NFs). This resulted in the formation of CuO-SnO2 NFs (full oxidation), Cu-SnO2 NFs (selective reduction), Cu3Sn/CNFs, Cu41Sn11/CNFs, and Cu6Sn5/CNFs (full reduction). In the CO2RR, CuO-SnO2 NFs exhibited formate (HCOO−) production and Cu-SnO2 NFs showed carbon monoxide (CO) production with the faradaic efficiency (FE) of 65.3% at −0.99 V (vs. RHE) and 59.1% at −0.89 V (vs. RHE) respectively. Cu-rich Cu41Sn11/CNFs and Cu3Sn/CNFs enhanced the methane (CH4) production with the FE of 39.1% at −1.36 V (vs. RHE) and 34.7% at −1.50 V (vs. RHE). However, Sn-rich Cu6Sn5/CNFs produced HCOO− with the FE of 58.6% at −2.31 V (vs. RHE). This study suggests the methodology for bimetallic catalyst design and steering the CO2RR pathway by controlling the active sites of Cu-Sn alloys. © 2024 The Royal Society of Chemistry. Thu, 31 Oct 2024 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/57430 2024-10-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/57167 Title: Porous Cu/C nanofibers promote electrochemical CO2-to-ethylene conversion via high CO2 availability Author(s): Bae, Daewon; Lee, Taemin; Kwon, Woosuck; Oh, Sang-Ho; Nam, Dae-Hyun Abstract: In the CO2 reduction reaction (CO2RR), efficient CO2 mass transport is important to facilitate CO2-to-ethylene (C2H4) conversion which requires *CO dimerization. Here, we report carbon (C) shell-augmented Cu-embedded porous C nanofibers (CNFs) to elucidate the effects of mesoporous C on CO2-to-C2H4 conversion. The mesoporous C structures were controlled by harnessing blended polymers (PAN + PMMA) which have distinct thermal decomposition behaviors and by inducing selective C oxidation during calcination. Furthermore, we found that selective C oxidation can induce the C precipitation from the CO (g) and CO2 (g) by the Boudouard reaction. This enabled the formation of C shells on the surface of Cu active sites. C shell-augmented Cu/CNFs having the highest surface area of mesopores enhanced the CO2 mass transport and CO2 adsorption for high CO2 availability. Porous Cu/CNFs, fabricated by the calcination of electrospun Cu-precursor + blended polymer nanofibers (NFs) with the 60% PMMA ratio and selective C oxidation, induced an efficient C2H4 faradaic efficiency (FE) of 39.5% at −1.27 V (vs. RHE), 1.7-fold improvement from the C2H4 FE of 23.2% at −1.25 V (vs. RHE) in Cu/CNFs, fabricated by full reduction without PMMA (the lowest surface area of mesopores). Investigating the CO2RR under CO2 deficient conditions and analyzing the in situ Raman spectra reveal that enhanced CO2 mass transport and CO2 adsorption can facilitate CO2 availability with high *CO coverage for efficient C2H4 production. © 2024 The Royal Society of Chemistry. Sun, 30 Jun 2024 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/57167 2024-06-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/57132 Title: Predictive Synthesis of Transition Metal Carbide via Thermochemical Oxocarbon Equilibrium Author(s): Oh, Sang-Ho; Kim, Dohun; Kim, Ji-Yong; Kang, Geosan; Jeon, Jooyoung; Kim, Miyoung; Joo, Young-Chang; Nam, Dae-Hyun Abstract: Fabricating nanoscale metal carbides is a great challenge due to them having higher Gibbs free energy of formation (ΔG°) values than other metal compounds; additionally, these carbides have harsh calcination conditions, in which metal oxidation is preferred in the atmosphere. Herein, we report oxocarbon-mediated calcination for the predictive synthesis of nanoscale metal carbides. The thermochemical oxocarbon equilibrium of CO-CO2 reactions was utilized to control the selective redox reactions in multiatomic systems of Mo-C-O, contributing to the phase-forming and structuring of Mo compounds. By harnessing the thermodynamically predicted processing window, we controlled a wide range of Mo phases (MoO2, α-MoC1-x, and β-Mo2C) and nanostructures (nanoparticle, spike, stain, and core/shell) in the Mo compounds/C nanofibers. By inducing simultaneous reactions of C-O (selective C combustion) and Mo-C (Mo carbide formation) in the nanofibers, Mo diffusion was controlled in C nanofibers, acting as a template for the nucleation and growth of Mo carbides and resulting in precise control of the phases and structures of Mo compounds. The formation mechanism of nanostructured Mo carbides was elucidated according to the CO fractions of CO-CO2 calcination. Moreover, tungsten (W) and niobium (Nb) carbides/C nanofibers have been successfully synthesized by CO-CO2 calcination. We constructed the thermodynamic map for the predictive synthesis of transition metal carbides to provide universal guideline via thermochemical oxocarbon equilibrium. We revealed that our thermochemical oxocarbon-mediated gas-solid reaction enabled the structure and phase control of nanoscale transition metal compounds to optimize the material-property relationship accordingly. © 2024 American Chemical Society Tue, 30 Apr 2024 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/57132 2024-04-30T15:00:00Z