Browsing by Author "Shirzadi, Erfan"
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Item Carbon- and energy-efficient ethanol electrosynthesis via interfacial cation enrichment(Springer Science and Business Media LLC, 2024-10-04) Shayesteh Zeraati, Ali; Li, Feng; Tartela Alkayyali, Tartela; Dorakhan, Roham; Shirzadi, Erfan; Arabyarmohammadi, Fatemeh; O’Brien, Colin P; Gabardo, Christine M; Kong, Jonathan; Ozden, Adnan; Zargartalebi, Mohammad; Zhao, Yong; Fan, Lizhou; Papangelakis, Panagiotis; Kim, Dongha; Park, Sungjin; Miao, Rui Kai; Edwards, Jonathan P; Young, Daniel; Ip, Alexander H; Sargent, Edward H; Sinton, DavidThe use of acidic electrolytes in CO2 reduction avoids costly carbonate loss. However, the energy efficiency of acid-fed electrolysers has been limited by high hydrogen production and operating potentials. We find that these stem from the lack of alkali cations at the catalyst surface, limiting CO2 and CO adsorption. In acid-fed membrane electrode assembly systems, the incorporation of these cations is challenging as there is no flowing catholyte. Here an interfacial cation matrix (ICM)–catalyst heterojunction is designed that directly attaches to the catalyst layer. The negatively charged nature of the ICM enriches the alkali cation concentration near the cathode surface, trapping generated hydroxide ions. This increases the local electric field and pH, increasing multi-carbon production. Integrating the ICM strategy with a tailored copper–silver catalyst enables selective ethanol production through a proton-spillover mechanism. We report a 45% CO2-to-ethanol Faradaic efficiency at 200 mA cm−2, carbon efficiency of 63%, full-cell ethanol energy efficiency of 15% (3-fold improvement over the best previous acidic CO2 reduction value) and energy cost of 260 GJ per tonne ethanol, the lowest among reported ethanol-producing CO2 electrolysers.Item Ligand-modified nanoparticle surfaces influence CO electroreduction selectivity(Nature Research, 2024-04-06) Shirzadi, Erfan; Jin, Qiu; Zeraati, Ali Shayesteh; Dorakhan, Roham; Goncalves, Tiago J; Abed, Jehad; Lee, Byoung-Hoon; Rasouli, Armin Sedighian; Wicks, Joshua; Zhang, Jinqiang; Ou, Pengfei; Boureau, Victor; Park, Sungjin; Ni, Weiyan; Lee, Geonhui; Tian, Cong; Meira, Debora Motta; Sinton, David; Siahrostami, Samira; Sargent, Edward HImproving the kinetics and selectivity of CO2/CO electroreduction to valuable multi-carbon products is a challenge for science and is a requirement for practical relevance. Here we develop a thiol-modified surface ligand strategy that promotes electrochemical CO-to-acetate. We explore a picture wherein nucleophilic interaction between the lone pairs of sulfur and the empty orbitals of reaction intermediates contributes to making the acetate pathway more energetically accessible. Density functional theory calculations and Raman spectroscopy suggest a mechanism where the nucleophilic interaction increases the sp2 hybridization of CO(ad), facilitating the rate-determining step, CO* to (CHO)*. We find that the ligands stabilize the (HOOC-CH2)* intermediate, a key intermediate in the acetate pathway. In-situ Raman spectroscopy shows shifts in C-O, Cu-C, and C-S vibrational frequencies that agree with a picture of surface ligand-intermediate interactions. A Faradaic efficiency of 70% is obtained on optimized thiol-capped Cu catalysts, with onset potentials 100 mV lower than in the case of reference Cu catalysts.Item Paired Electrosynthesis of H2 and Acetic Acid at A/cm2 Current Densities(ACS, 2023-09-11) Tian, Cong; Li, Xiao-Yan; Nelson, Vivian E.; Ou, Pengfei; Zhou, Daojin; Chen, Yuanjun; Zhang, Jinqiang; Huang, Jianan Erick; Wang, Ning; Yu, Jiaqi; Liu, Hengzhou; Liu, Cheng; Yang, Yi; Peng, Tao; Zhao, Yong; Lee, Byoung-Hoon; Wang, Sasa; Shirzadi, Erfan; Chen, Zhu; Miao, Rui Kai; Sinton, David; Sargent, Edward H.Industrial water splitting pairs cathodic hydrogen evolution with oxygen evolution at the anode, the latter generating low-value oxygen as the oxidative product. We reasoned that replacing the oxygen evolution reaction (OER) with anodic electrosynthesis of acetic acid from ethanol at industrial current densities could be a route to increase the economic efficiency of green hydrogen production. We partition the selective oxidation of ethanol to acetic acid into two mechanistically distinct transformations: first ethanol oxidation followed by the production of *OH. Density functional theory (DFT) studies show that the aldehyde-derived intermediate CH3CO* from ethanol oxidation and the *OH radical from water dissociation are both needed in the electroproduction of acetic acid. Operando Fourier transform infrared (FTIR) spectroscopy identifies the corresponding aldehyde intermediates on the anode surface. Based on these mechanistic findings, we develop a vacancy-rich IrRuOx catalyst and achieve selective electrotransformation of ethanol to acetic acid at a generation rate of 30 mmol/cm2/h and a partial current density of 3 A/cm2, fully 10× higher than in the previous highest-activity reports.Item A silver–copper oxide catalyst for acetate electrosynthesis from carbon monoxide(Nature Research, 2023-03-13) Dorakhan, Roham; Grigioni, Ivan; Lee, Byoung-Hoon; Ou, Pengfei; Abed, Jehad; O’Brien, Colin; Sedighian Rasouli, Armin; Plodinec, Milivoj; Miao, Rui Kai; Shirzadi, Erfan; Wicks, Joshua; Park, Sungjin; Lee, Geonhui; Zhang, Jinqiang; Sinton, David; Sargent, Edward H.Acetic acid is an important chemical feedstock. The electrocatalytic synthesis of acetic acid from CO2 offers a low-carbon alternative to traditional synthetic routes, but the direct reduction from CO2 comes with a CO2 crossover energy penalty. CO electroreduction bypasses this, which motivates the interest in a cascade synthesis approach of CO2 to CO followed by CO to acetic acid. Here we report a catalyst design strategy in which off-target intermediates (such as ethylene and ethanol) in the reduction of CO to acetate are destabilized. On the optimized Ag–CuO2 catalyst, this destabilization of off-target intermediates leads to an acetate Faradaic efficiency of 70% at 200 mA cm−2. We demonstrate 18 hours of stable operation in a membrane electrode assembly; the system produced 5 wt% acetate at 100 mA cm−2 and a full-cell energy efficiency of 25%, a twofold improvement on the highest energy-efficient electrosynthesis in prior reports.Item Supramolecular tuning of supported metal phthalocyanine catalysts for hydrogen peroxide electrosynthesis(Nature Research, 2023-03-13) Lee, Byoung-Hoon; Shin, Heejong; Rasouli, Armin Sedighian; Choubisa, Hitarth; Ou, Pengfei; Dorakhan, Roham; Grigioni, Ivan; Lee, Geonhui; Shirzadi, Erfan; Miao, Rui Kai; Wicks, Joshua; Park, Sungjin; Lee, Hyeon Seok; Zhang, Jinqiang; Chen, Yuanjun; Chen, Zhu; Sinton, David; Hyeon, Taeghwan; Sung, Yung-Eun; Sargent, Edward H.Two-electron oxygen reduction offers a route to H2O2 that is potentially cost-effective and less energy-intensive than the industrial anthraquinone process. However, the catalytic performance of the highest performing prior heterogeneous electrocatalysts to H2O2 has lain well below the >300 mA cm−2 needed for capital efficiency. Herein, guided by computation, we present a supramolecular approach that utilizes oxygen functional groups in a carbon nanotube substrate that—when coupled with a cobalt phthalocyanine catalyst—improve cobalt phthalocyanine adsorption, preventing agglomeration; and that further generate an electron-deficient Co centre whose interaction with the key H2O2 intermediate is tuned towards optimality. The catalysts exhibit an overpotential of 280 mV at 300 mA cm−2 with turnover frequencies over 50 s−1 in a neutral medium, an order of magnitude higher activity compared with the highest performing prior H2O2 electrocatalysts. This performance is sustained for over 100 h of operation.Item Surface hydroxide promotes CO2 electrolysis to ethylene in acidic conditions(Nature Research, 2023-04-25) Cao, Yufei; Chen, Zhu; Li, Peihao; Ozden, Adnan; Ou, Pengfei; Ni, Weiyan; Abed, Jehad; Shirzadi, Erfan; Zhang, Jinqiang; Sinton, David; Ge, Jun; Sargent, Edward HPerforming CO2 reduction in acidic conditions enables high single-pass CO2 conversion efficiency. However, a faster kinetics of the hydrogen evolution reaction compared to CO2 reduction limits the selectivity toward multicarbon products. Prior studies have shown that adsorbed hydroxide on the Cu surface promotes CO2 reduction in neutral and alkaline conditions. We posited that limited adsorbed hydroxide species in acidic CO2 reduction could contribute to a low selectivity to multicarbon products. Here we report an electrodeposited Cu catalyst that suppresses hydrogen formation and promotes selective CO2 reduction in acidic conditions. Using in situ time-resolved Raman spectroscopy, we show that a high concentration of CO and OH on the catalyst surface promotes C-C coupling, a finding that we correlate with evidence of increased CO residence time. The optimized electrodeposited Cu catalyst achieves a 60% faradaic efficiency for ethylene and 90% for multicarbon products. When deployed in a slim flow cell, the catalyst attains a 20% energy efficiency to ethylene, and 30% to multicarbon products.