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Jiacheng Chen

Bio: Jiacheng Chen is an academic researcher from East China University of Science and Technology. The author has contributed to research in topics: Catalysis & Chemistry. The author has an hindex of 9, co-authored 21 publications receiving 312 citations.

Papers
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Journal ArticleDOI
TL;DR: This work proposes a new strategy to covalently graft cobalt porphyrin onto the surface of a carbon nanotube by a substitution reaction at the metal center, providing an effective pathway for the improvement of the performance of electrocatalysts that could inspire rational design of molecular catalysts in the future.
Abstract: Molecular complexes with inexpensive transition-metal centers have drawn extensive attention, as they show a high selectivity in the electrochemical conversion of CO2 to CO. In this work, we propose a new strategy to covalently graft cobalt porphyrin onto the surface of a carbon nanotube by a substitution reaction at the metal center. Material characterization and electrochemical studies reveal that the porphyrin molecules are well dispersed at a high loading of 10 wt. %. As a result, the turnover frequency for CO formation is improved by a factor of three compared to traditional physically-mixed catalysts with the same cobalt content. This leads to an outstanding overall current density of 25.1 mA cm-2 and a Faradaic efficiency of 98.3 % at 490 mV overpotential with excellent long-term stability. This work provides an effective pathway for the improvement of the performance of electrocatalysts that could inspire rational design of molecular catalysts in the future.

176 citations

Journal ArticleDOI
TL;DR: In this article, a cobalt phthalocyanine-based catalyst supported on pyridine-functionalized carbon nanotubes (CoPc-py-CNT) was designed for electrochemical CO2 reduction.
Abstract: Electrochemical reduction of CO2 is promising to utilize the intermittent renewable electricity and transform CO2 into value-added products, simultaneously. Herein, we designed a cobalt phthalocyanine-based catalyst supported on pyridine-functionalized carbon nanotubes (CoPc-py-CNT). This novel hybrid catalyst exhibited a high activity (TOFCO: 34.5 s−1 at −0.63 V vs. RHE) and selectivity (FECO > 98%) for electrochemical CO2 reduction. To the best of our knowledge, it is the best one among all reported molecular based electrocatalysts for CO2-to-CO conversion. Furthermore, structure characterizations (such as Raman and X-rays photoelectron spectroscopy), loading-dependent electrochemical analysis and mechanistic studies revealed that pyridine groups, through axial coordination with Co, not only functioned as physical promoters to improve the dispersion of cobalt phthalocyanine but also tuned the electronic structure of Co sites to increase the intrinsic turnover frequency.

122 citations

Journal ArticleDOI
TL;DR: In situ characterization combined with density functional theory (DFT) calculations reveals that heteronuclear coordination modifies the d-states of the metal atom, resulting in a lower free energy barrier in the thermodynamic pathway and a reduced activation energy as well as fortified metal-C bonding in the kinetic pathway.
Abstract: Dual-atom catalysts have the potential to outperform the well-established single-atom catalysts for the electrochemical conversion of CO2 . However, the lack of understanding regarding the mechanism of this enhanced catalytic process prevents the rational design of high-performance catalysts. Herein, an obvious synergistic effect in atomically dispersed Ni-Zn bimetal sites is observed. In situ characterization combined with density functional theory (DFT) calculations reveals that heteronuclear coordination modifies the d-states of the metal atom, narrowing the gap between the d-band centre (ed ) of the Ni (3d) orbitals and the Fermi energy level (EF ) to strengthen the electronic interaction at the reaction interface, resulting in a lower free energy barrier (ΔG) in the thermodynamic pathway and a reduced activation energy (Ea ) as well as fortified metal-C bonding in the kinetic pathway. Consequently, a CO faradaic efficiency of >90% is obtained across a broad potential window from -0.5 to -1.0 V (vs RHE), reaching a maximum of 99% at -0.8 V, superior to that of the Ni/Zn single-metal sites.

99 citations

Journal ArticleDOI
TL;DR: In this article, a Y2O3-promoted NiO-CeO2 catalyst was proposed and found to exhibit an outstanding methanation activity that is up to three folds higher than NiOCe O2 and six fold higher than NO-Y 2 O3 at mild reaction temperatures.
Abstract: It is challenging to elucidate the mechanism of CO2 methanation reaction over nickel-based catalysts and precisely tune the kinetics of rate-determining-step. In this work, we propose a strategy to engineer the oxygen vacancies of nickel-based catalysts for enhanced CO2 methanation. A Y2O3-promoted NiO-CeO2 catalyst is prepared and found to exhibit an outstanding methanation activity that is up to three folds higher than NiO-CeO2 and six folds higher than NiO-Y2O3 at mild reaction temperatures (

87 citations

Journal ArticleDOI
TL;DR: For the first time, it is reported that by varying the metal ratio, the catalyst can be tuned from a core-shell structure that selectively produces CO to a well-mixed structure that prefers HCOOH production.
Abstract: Selectively approaching chemicals with one composition-tunable catalyst is attractive for practical manufacturing. Bimetallic copper-indium (Cu-In) catalysts have been synthesized by using a coprecipitation method and found to be among the best reported In-based catalysts for electrochemical CO2 reduction to CO or HCOOH. By varying the metal ratio, the catalyst can be tuned from a core-shell structure that selectively produces CO to a well-mixed structure that prefers HCOOH production. The distinct selectivities depend on the structure-sensitive binding strength of key reactive intermediates. These findings can benefit the development of a broader range of selectivity-tunable catalysts.

47 citations


Cited by
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Journal ArticleDOI
TL;DR: Experiments and density functional theory results demonstrate single-atom Bi-N4 site is the dominating active center simultaneously for CO2 activation and the rapid formation of key inter-mediate COOH* with low free energy barrier.
Abstract: The electrocatalytic reduction reaction of CO2 (CO2RR) is a promising strategy to promote the global carbon balance and combat global climate change. Herein, exclusive Bi-N4 sites on porous carbon ...

397 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a rather comprehensive review of the recent research progress, in the view of associated value-added products upon selective electrocatalytic CO2 conversion.
Abstract: The continuously increasing CO2 released from human activities poses a great threat to human survival by fluctuating global climate and disturbing carbon balance among the four reservoirs of the biosphere, earth, air, and water. Converting CO2 to value-added feedstocks via electrocatalysis of the CO2 reduction reaction (CO2RR) has been regarded as one of the most attractive routes to re-balance the carbon cycle, thanks to its multiple advantages of mild operating conditions, easy handling, tunable products and the potential of synergy with the rapidly increasing renewable energy (i.e., solar, wind). Instead of focusing on a special topic of electrocatalysts for the CO2RR that have been extensively reviewed elsewhere, we herein present a rather comprehensive review of the recent research progress, in the view of associated value-added products upon selective electrocatalytic CO2 conversion. We initially provide an overview of the history and the fundamental science regarding the electrocatalytic CO2RR, with a special introduction to the design, preparation, and performance evaluation of electrocatalysts, the factors influencing the CO2RR, and the associated theoretical calculations. Emphasis will then be given to the emerging trends of selective electrocatalytic conversion of CO2 into a variety of value-added products. The structure-performance relationship and mechanism will also be discussed and investigated. The outlooks for CO2 electrocatalysis, including the challenges and opportunities in the development of new electrocatalysts, electrolyzers, the recently rising operando fundamental studies, and the feasibility of industrial applications are finally summarized.

387 citations

Journal ArticleDOI
TL;DR: Zhang et al. as discussed by the authors designed a series of nickel phthalocyanine molecules supported on carbon nanotubes as molecularly dispersed electrocatalysts (MDEs), achieving CO2 reduction performances that are superior to aggregated molecular catalysts in terms of stability, activity and selectivity.
Abstract: Electrochemical reduction of CO2 is a promising route for sustainable production of fuels. A grand challenge is developing low-cost and efficient electrocatalysts that can enable rapid conversion with high product selectivity. Here we design a series of nickel phthalocyanine molecules supported on carbon nanotubes as molecularly dispersed electrocatalysts (MDEs), achieving CO2 reduction performances that are superior to aggregated molecular catalysts in terms of stability, activity and selectivity. The optimized MDE with methoxy group functionalization solves the stability issue of the original nickel phthalocyanine catalyst and catalyses the conversion of CO2 to CO with >99.5% selectivity at high current densities of up to −300 mA cm−2 in a gas diffusion electrode device with stable operation at −150 mA cm−2 for 40 h. The well-defined active sites of MDEs also facilitate the in-depth mechanistic understandings from in situ/operando X-ray absorption spectroscopy and theoretical calculations on structural factors that affect electrocatalytic performance. Widespread deployment of electrochemical CO2 reduction requires low-cost catalysts that perform well at high current densities. Zhang et al. show that methoxy-functionalized nickel phthalocyanine molecules on carbon nanotubes can operate as high-performing molecularly dispersed electrocatalysts at current densities of up to −300 mA cm–2.

287 citations

Posted Content
01 Feb 2020-viXra
TL;DR: In this article, the authors discuss strategies to achieve high C2+ selectivity through rational design of the catalyst and electrolyte, focusing on findings extracted from in situ and operando characterizations.
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.

259 citations

Journal ArticleDOI
TL;DR: This work has developed a facile strategy to the manipulation of the cobalt spin state over covalent organic frameworks, COF-367-Co, by simply changing the oxidation state of Co centered in the porphyrin to regulate photocatalysis by spin state manipulation in COFs.
Abstract: While catalysis is highly dependent on the electronic structure of the catalyst, the understanding of catalytic performance affected by electron spin regulation remains challenging and rare. Herein, we have developed a facile strategy to the manipulation of the cobalt spin state over covalent organic frameworks (COFs), COF-367-Co, by simply changing the oxidation state of Co centered in the porphyrin. Density functional theory (DFT) calculations together with experimental results confirm that CoII and CoIII are embedded in COF-367 with S = 1/2 and 0 spin ground states, respectively. Remarkably, photocatalytic CO2 reduction results indicate that COF-367-CoIII exhibits favorable activity and significantly enhanced selectivity to HCOOH, accordingly much reduced activity and selectivity to CO and CH4, in sharp contrast to COF-367-CoII. The results highlight that the spin-state transition of cobalt greatly regulates photocatalytic performance. Theoretical calculations further disclose that the presence of CoIII in COF-367-Co is preferable to the formation of HCOOH but detrimental to its further conversion, which clearly accounts for its distinctly different photocatalysis over COF-367-CoII. To the best of our knowledge, this is the first report on regulating photocatalysis by spin state manipulation in COFs.

255 citations