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Published in Chad A. Mirkin, Spherical Nucleic Acids, 2020
Christine R. Laramy, Matthew N. O’Brien, Chad A. Mirkin
The precise positioning of nanoscale components may also benefit the catalysis field, in particular, tandem catalysis. Tandem catalysis pairs catalysts with complementary functions (for example, the product of one reaction acts as the reactant for a second reaction) and thus can increase reaction yield and selectivity [240–242]. Studies have revealed that colloidal crystals comprised of spherical gold nanoparticles can act as catalysts upon transfer to a solid-state matrix and the subsequent removal of DNA [231]. In principle, the structural control afforded by crystal engineering with DNA could facilitate tandem catalysis for inorganic systems, such as Au/Pd nanoparticles, or organic catalysis, as with enzymes. For example, DNA can arrange and orientate proteins with respect to one another [162, 163]. If enzymatic proteins were similarly modified with DNA and crystallized, these building blocks could form a cascade in which the active site of one would be orientated to face that of the next enzyme for efficient multistep syntheses. Realization of this cascade requires exploration of the fundamental relationship between enzyme spacing and catalytic efficiency. At long distances between enzymes, the products of one enzyme may diffuse away before they can act as reactants for the next enzyme, and at short distances, steric hindrance may prevent access of reactants to active sites or release of products from active sites.
Organocatalysis with carbon nitrides
Published in Science and Technology of Advanced Materials, 2023
Sujanya Maria Ruban, Kavitha Ramadass, Gurwinder Singh, Siddulu Naidu Talapaneni, Gunda Kamalakar, Chandrakanth Rajanna Gadipelly, Lakshmi Kantham Mannepalli, Yoshihiro Sugi, Ajayan Vinu
Several reviews on the catalysis of carbon nitrides, especially in photocatalytic water splitting and in organic synthesis, have appeared in the literature that contributed to enhancing the research in the catalysis of carbon nitrides [19,32–36]. In this review, we discuss primarily the base and photo-redox catalyses of these materials in organic synthesis with a focus on Knoevenagel condensation, the cycloaddition of carbon dioxide (CO2) on epoxides, oxidation, hydrogenation, esterification, trans-esterification and hydrolysis as the typical catalysis examples. The use of carbon nitrides for tandem catalysis and the basic catalyst support combined with the other functional catalysts are also considered with and without illumination. The metal-free catalysis of the carbon nitrides involving hydrogenation and oxidation is also discussed. Further, we discuss the use of carbon nitride catalysis for application in organic synthesis and biomimetic catalysis.
Recent development of integrating CO2 hydrogenation into methanol with ocean thermal energy conversion (OTEC) as potential source of green energy
Published in Green Chemistry Letters and Reviews, 2023
Mohd Hizami Mohd Yusoff, Lau Kok Keong, Nor Hafizah Yasin, Mohammad Syamzari Rafeen, Amiruddin Hassan, Geetha Srinivasan, Suzana Yusup, Azmi Mohd Shariff, A. Bakar Jaafar
Recently, few studies have been conducted on the CO2 hydrogenation; Table 2 summarizes the catalytic hydrogenation of CO2 to green hydrocarbons. Rezayee et al. (34) investigated the production of methanol from CO2 using a ruthenium catalyst in the presence of dimethylamine. The CO2 to methanol conversion of greater than 95% was achieved using tandem catalysis. Jiang et al. (35) investigated the production of methanol using a series of catalysts consisting of Pd/In2O3/SBA-15 catalysts that were synthesized by the citric acid method. In another study, copper and zinc oxide composite was utilized to produce methanol by keeping the operating conditions of reaction temperature of 250°C, reaction pressure of 3.0 MPa, H2: CO2 ratio of 3:1. The overall carbon dioxide conversion of 11% was obtained at the optimized conditions (36). In another study, Samson et al. (27) studied the Cu with ZrO2 as the catalyst support for the reaction conditions of reaction temperature of 260°C, reaction pressure of 8.0 MPa, H2: CO2 ratio of 3:1. 86% of methanol yield was achieved at the optimized conditions with 15% of CO2 selectivity.
RETRACTED ARTICLE: Preparation of hollow Aux-Cu2O nanospheres by galvanic replacement to enhance the selective electrocatalytic CO2 reduction to ethanol
Published in Journal of Experimental Nanoscience, 2022
Lijie Zhang, Ying Zhang, Hongtao Wang, Jianbing Chen, Zhongqi Cao
In our study, hollow Aux-Cu2O electrocatalysts were designed based on the tandem catalysis mechanism. The role of Au is to promote the conversion of CO2 to CO, which is beneficial to increase the local concentration of the key intermediate *CO in order to promote the C–C bond coupling reaction, and then enhance the formation of multi-carbon products. Firstly, hollow Cu2O nanospheres were prepared with CTAB (Hexadecyl trimethyl ammonium Bromide) as a soft template, and hollow Aux-Cu2O electrocatalysts were prepared by galvanic replacement. The physical and chemical properties and electrochemical properties of the prepared electrocatalysts were characterized, and the performance of CO2 reduction to ethanol was evaluated.