Hyo Sang Jeon

Bio: Hyo Sang Jeon is an academic researcher from Fritz Haber Institute of the Max Planck Society. The author has contributed to research in topics: Catalysis & Overpotential. The author has an hindex of 22, co-authored 46 publications receiving 2278 citations. Previous affiliations of Hyo Sang Jeon include Ruhr University Bochum & Korea Institute of Science and Technology.

Rational catalyst and electrolyte design for CO2 electroreduction towards multicarbon products

Abstract: The CO2 electroreduction reaction (CO2RR) to fuels and feedstocks is an attractive route to close the anthropogenic carbon cycle and store renewable energy. The generation of more reduced chemicals, especially multicarbon oxygenate and hydrocarbon products (C2+) with higher energy densities, is highly desirable for industrial applications. However, selective conversion of CO2 to C2+ suffers from a high overpotential, a low reaction rate and low selectivity, and the process is extremely sensitive to the catalyst structure and electrolyte. Here we discuss strategies to achieve high C2+ selectivity through rational design of the catalyst and electrolyte. Current state-of-the-art catalysts, including Cu and Cu–bimetallic catalysts, as well as some alternative materials, are considered. The importance of taking into consideration the dynamic evolution of the catalyst structure and composition are highlighted, focusing on findings extracted from in situ and operando characterizations. Additional theoretical insight into the reaction mechanisms underlying the improved C2+ selectivity of specific catalyst geometries and compositions in synergy with a well-chosen electrolyte are also provided. The electrochemical reduction of carbon dioxide to fuels and feedstocks has received increased attention over the past few years. In this Review, Roldan Cuenya and co-workers discuss strategies to achieve high selectivity towards multicarbon products via rational catalyst and electrolyte design.

Achieving Selective and Efficient Electrocatalytic Activity for CO2 Reduction Using Immobilized Silver Nanoparticles.

Abstract: Selective electrochemical reduction of CO2 is one of the most sought-after processes because of the potential to convert a harmful greenhouse gas to a useful chemical. We have discovered that immobilized Ag nanoparticles supported on carbon exhibit enhanced Faradaic efficiency and a lower overpotential for selective reduction of CO2 to CO. These electrocatalysts were synthesized directly on the carbon support by a facile one-pot method using a cysteamine anchoring agent resulting in controlled monodispersed particle sizes. These synthesized Ag/C electrodes showed improved activities, specifically decrease of the overpotential by 300 mV at 1 mA/cm2, and 4-fold enhanced CO Faradaic efficiency at −0.75 V vs RHE with the optimal particle size of 5 nm compared to polycrystalline Ag foil. DFT calculations enlightened that the specific interaction between Ag nanoparticle and the anchoring agents modified the catalyst surface to have a selectively higher affinity to the intermediate COOH over CO, which effectivel...

Rational Catalyst and Electrolyte Design for Co2 Electroreduction Towards Multicarbon Products

Abstract: CO2 electroreduction reaction (CO2RR) to fuels and feedstocks is an attractive route to close the anthropogenic carbon cycle and store renewable energy. The generation of more reduced chemicals, especially multicarbon oxygenate and hydrocarbon products (C2+) with higher energy density is highly desirable for industrial applications. However, selective conversion of CO2 to C2+ suffers from high overpotential, low reaction rate and low selectivity, and the process is extremely sensitive to the catalyst structure and electrolyte. Here we discuss strategies to achieve high C2+ selectivity through rational design of the catalyst and electrolyte. Current state-of-the-art catalysts, including Cu and Cu-bimetallic catalysts as well as alternative materials are considered. The importance of taking into consideration the dynamic evolution of the catalyst structure and composition are highlighted, focusing on findings extracted from in situ and operando characterizations. Additional theoretical insight into the reaction mechanisms underlying the improved C2+ selectivity of specific catalyst geometries/compositions in synergy with a well-chosen electrolyte are also provided.

Transition metal-based catalysts for the electrochemical CO2 reduction: from atoms and molecules to nanostructured materials

Abstract: The electrochemical reduction of carbon dioxide (CO2) powered by renewable energy is an attractive sustainable approach to mitigate CO2 emissions and to produce fuels or value-added chemicals. In order to tackle the challenges related to selectivity, activity, overpotential and durability, transition metal-based catalysts have been widely investigated in the last decades. In an effort to bridge the gap between the fields of homogeneous and heterogeneous catalysis, this review aims to survey the main strategies explored for the rational design of a wide variety of different metal catalysts, ranging from molecular systems to single-atom and nanostructured catalysts. Transition metal complexes containing heme and non-heme ligands have been selected to discuss the recent advances in the understanding of the structure–function relationship in molecular homogeneous catalysis as well as to summarize the main approaches proposed for the heterogenization or confinement of molecular catalysts on conductive surfaces. The main strategies to minimize catalyst cost are also presented, leading to atomically dispersed molecular-like M–Nx moieties embedded on 2D conducting materials. The superior performances of single-atom catalysts (SACs) and the structural similarity with their molecular analogs, suggest that transition metal catalysts containing well-defined sites may be intrinsically more active and selective towards CO2 conversion than the bulk heterogeneous materials. Finally, design approaches for metal nanoparticles (NPs) based on size, shape, and support tuning are summarized and compared to novel strategies based on the interaction with surface-bonded organic molecules. The studies herein presented show that the basic principles in molecular catalysis and organometallic chemistry can be effectively used to design new efficient and selective heterogeneous catalysts for CO2 reduction.

Enhanced Carbon Dioxide Electroreduction to Carbon Monoxide over Defect-Rich Plasma-Activated Silver Catalysts

Abstract: Efficient, stable catalysts with high selectivity for a single product are essential to making the electroreduction of CO2 a viable route to the synthesis of industrial feedstocks and fuels. We reveal how a plasma oxidation pre-treatment can lead to an enhanced content of low-coordinated active sites which dramatically lower the overpotential and increase the activity of CO2 electroreduction to CO. At -0.6 V vs. RHE, more than 90% Faradaic efficiency towards CO could be achieved on a pre-oxidized silver foil. While transmission electron microscopy and operando X-ray absorption spectroscopy showed that oxygen species can survive in the bulk of the catalyst during the reaction, in situ X-ray photoelectron spectroscopy showed that the surface is metallic under reaction conditions. DFT calculations show how the defect-rich surface of the plasma-oxidized silver foils in the presence of local electric fields results in a drastic decrease in the overpotential for the electroreduction of CO2.

Engineering heterogeneous semiconductors for solar water splitting

Abstract: There is a growing interest in the conversion of water and solar energy into clean and renewable H2 fuels using earth-abundant materials due to the depletion of fossil fuel and its serious environmental impact. This critical review highlights some key factors influencing the efficiency of heterogeneous semiconductors for solar water splitting (i.e. improved charge separation and transfer, promoted optical absorption, optimized band gap position, lowered cost and toxicity, and enhanced stability and water splitting kinetics). Moreover, different engineering strategies, such as band structure engineering, micro/nano engineering, bionic engineering, co-catalyst engineering, surface/interface engineering of heterogeneous semiconductors are summarized and discussed thoroughly. The synergistic effects of the different engineering strategies, especially for the combination of co-catalyst loading and other strategies seem to be more promising for the development of highly efficient photocatalysts. A thorough understanding of electron and hole transfer thermodynamics and kinetics at the fundamental level is also important for elucidating the key efficiency-limiting step and designing highly efficient solar-to-fuel conversion systems. In this review, we provide not only a summary of the recent progress in the different engineering strategies of heterogeneous semiconductors for solar water splitting, but also some potential opportunities for designing and optimizing solar cells, photocatalysts for the reduction of CO2 and pollutant degradation, and electrocatalysts for water splitting.

Atomically dispersed Ni(i) as the active site for electrochemical CO2 reduction

Abstract: Electrochemical reduction of CO2 to chemical fuel offers a promising strategy for managing the global carbon balance, but presents challenges for chemistry due to the lack of effective electrocatalyst. Here we report atomically dispersed nickel on nitrogenated graphene as an efficient and durable electrocatalyst for CO2 reduction. Based on operando X-ray absorption and photoelectron spectroscopy measurements, the monovalent Ni(i) atomic center with a d9 electronic configuration was identified as the catalytically active site. The single-Ni-atom catalyst exhibits high intrinsic CO2 reduction activity, reaching a specific current of 350 A gcatalyst−1 and turnover frequency of 14,800 h−1 at a mild overpotential of 0.61 V for CO conversion with 97% Faradaic efficiency. The catalyst maintained 98% of its initial activity after 100 h of continuous reaction at CO formation current densities as high as 22 mA cm−2. Electrocatalysts with improved activity and stability for the conversion of CO2 to CO are being sought. Using operando spectroscopies, the authors identify atomically dispersed Ni(i) as the active site in a nitrogenated-graphene-supported catalyst with high intrinsic activity and stability over 100 hours.

Cocatalysts for Selective Photoreduction of CO2 into Solar Fuels.

Abstract: Photoreduction of CO2 into sustainable and green solar fuels is generally believed to be an appealing solution to simultaneously overcome both environmental problems and energy crisis. The low selectivity of challenging multi-electron CO2 photoreduction reactions makes it one of the holy grails in heterogeneous photocatalysis. This Review highlights the important roles of cocatalysts in selective photocatalytic CO2 reduction into solar fuels using semiconductor catalysts. A special emphasis in this review is placed on the key role, design considerations and modification strategies of cocatalysts for CO2 photoreduction. Various cocatalysts, such as the biomimetic, metal-based, metal-free, and multifunctional ones, and their selectivity for CO2 photoreduction are summarized and discussed, along with the recent advances in this area. This Review provides useful information for the design of highly selective cocatalysts for photo(electro)reduction and electroreduction of CO2 and complements the existing reviews on various semiconductor photocatalysts.

Light-Driven Heterogeneous Reduction of Carbon Dioxide: Photocatalysts and Photoelectrodes

Abstract: Photocatalysts and Photoelectrodes James L. White,† Maor F. Baruch,† James E. Pander III,† Yuan Hu,† Ivy C. Fortmeyer,† James Eujin Park,† Tao Zhang,† Kuo Liao,† Jing Gu,‡ Yong Yan,‡ Travis W. Shaw,† Esta Abelev,† and Andrew B. Bocarsly*,† †Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States ‡Chemical and Materials Science Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States

Advances and challenges in understanding the electrocatalytic conversion of carbon dioxide to fuels

Abstract: The electrocatalytic reduction of carbon dioxide is a promising approach for storing (excess) renewable electricity as chemical energy in fuels. Here, we review recent advances and challenges in the understanding of electrochemical CO2 reduction. We discuss existing models for the initial activation of CO2 on the electrocatalyst and their importance for understanding selectivity. Carbon–carbon bond formation is also a key mechanistic step in CO2 electroreduction to high-density and high-value fuels. We show that both the initial CO2 activation and C–C bond formation are influenced by an intricate interplay between surface structure (both on the nano- and on the mesoscale), electrolyte effects (pH, buffer strength, ion effects) and mass transport conditions. This complex interplay is currently still far from being completely understood. In addition, we discuss recent progress in in situ spectroscopic techniques and computational techniques for mechanistic work. Finally, we identify some challenges in furthering our understanding of these themes. Electrocatalytic reduction of CO2 to fuels could be used as an approach to store renewable energy in the form of chemical energy. Here, Birdja et al. review current understanding of electrocatalytic systems and reaction pathways for these conversions.