[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

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.

Cocatalysts for Selective Photoreduction of CO2 into Solar Fuels.

We report selective electrocatalytic reduction of carbon dioxide to carbon monoxide on gold nanoparticles (NPs) in 0.5 M KHCO3 at 25 °C. Among monodisperse 4, 6, 8, and 10 nm NPs tested, the 8 nm Au NPs show the maximum Faradaic efficiency (FE) (up to 90% at −0.67 V vs reversible hydrogen electrode, RHE). Density functional theory calculations suggest that more edge sites (active for CO evolution) than corner sites (active for the competitive H2 evolution reaction) on the Au NP surface facilitates the stabilization of the reduction intermediates, such as COOH*, and the formation of CO. This mechanism is further supported by the fact that Au NPs embedded in a matrix of butyl-3-methylimidazolium hexafluorophosphate for more efficient COOH* stabilization exhibit even higher reaction activity (3 A/g mass activity) and selectivity (97% FE) at −0.52 V (vs RHE). The work demonstrates the great potentials of using monodisperse Au NPs to optimize the available reaction intermediate binding sites for efficient and ...

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Monodisperse Au nanoparticles for selective electrocatalytic reduction of CO2 to CO.

Recent advancements in supercapacitor technology

Electrografting refers to the electrochemical reaction that permits organic layers to be attached to solid conducting substrates. This definition can be extended to reactions involving an electron transfer between the substrate to be modified and the reagent, but also to examples where a reducing or oxidizing reagent is added to produce the reactive species. These methods are interesting as they provide a real bond between the surface and the organic layer. Electrografting applies to a variety of substrates including carbon, metals and their oxides, but also dielectrics such as polymers. Since the 1980s several methods have been developed, either by reduction or oxidation, and some of them have reached an industrial stage. This critical review describes the methods that are used for electrografting, their mechanism, the formation and growth of the layers as well as their applications (742 references).

Electrografting: a powerful method for surface modification

Conductive diamond possesses unique features as compared to other solid electrodes, such as a wide electrochemical potential window, a low and stable background current, relatively rapid rates of electron-transfer for soluble redox systems without conventional pretreatment, long-term responses, stability, biocompatibility, and a rich surface chemistry. Conductive diamond microcrystalline and nanocrystalline films, structures and particles have been prepared using a variety of approaches. Given these highly desirable attributes, conductive diamond has found extensive use as an enabling electrode across a variety of fields encompassing chemical and biochemical sensing, environmental degradation, electrosynthesis, electrocatalysis, and energy storage and conversion. This review provides an overview of the fundamental properties and highlights recent progress and achievements in the growth of boron-doped (metal-like) and nitrogen and phosphorus-doped (semi-conducting) diamond and hydrogen-terminated undoped diamond electrodes. Applications in electroanalysis, environmental degradation, electrosynthesis electrocatalysis, and electrochemical energy storage are also discussed. Diamond electrochemical devices utilizing micro-scale, ultramicro-scale, and nano-scale electrodes as well as their counterpart arrays are viewed. The challenges and future research directions of conductive diamond are discussed and outlined. This review will be important and informative for chemists, biochemists, physicists, materials scientists, and engineers engaged in the use of these novel forms of carbon.

Conductive diamond: synthesis, properties, and electrochemical applications

A summary of photo- and electrochemical surface modifications applied on single-crystalline chemical vapour deposition (CVD) diamond films is given. The covalently bonded formation of amine- and phenyl-linker molecule layers is characterized using x-ray photoelectron spectroscopy, atomic force microscopy (AFM), cyclic voltammetry and field-effect transistor characterization experiments. Amine- and phenyl-layers are very different with respect to formation, growth, thickness and molecule arrangement. We detect a single-molecular layer of amine-linker molecules on diamond with a density of about 1014?cm?2 (10% of carbon bonds). Amine molecules are bonded only on initially H-terminated surface areas to carbon. In the case of electrochemical deposition of phenyl-layers, multi-layer formation is detected due to three-dimensional (3D) growths. This gives rise to the formation of typically 25?? thick layers. The electrochemical grafting of boron-doped diamond works on H-terminated and oxidized surfaces.After reacting such films with hetero-bifunctional crosslinker molecules, thiol-modified ss-DNA markers are bonded to the organic system. Application of fluorescence and AFM on hybridized DNA films shows dense arrangements with densities of up to 1013?cm?2. The DNA is tilted by an angle of about 35? with respect to the diamond surface. Shortening the bonding time of thiol-modified ss-DNA to 10?min causes a decrease of DNA density to about 1012?cm?2. Application of AFM scratching experiments shows threshold removal forces of around 75?nN for DNA bonded on phenyl-linker molecules and of about 45?nN for DNA bonded to amine-linker molecules. DNA sensor applications using Fe(CN6)3?/4? mediator redox molecules, impedance spectroscopy and DNA-field effect transistor devices performances are introduced and discussed.

https://iopscience.iop.org/article/10.1088/0022-3727/40/20/S21/pdf

Diamond for bio-sensor applications

https://ora.ox.ac.uk/objects/uuid:986633c4-e60a-4470-b246-fa90e1bc437e/download_file?safe_filename=jnianjunCarbon_Diamond%2BNanoelectrochemistry_final.pdf&file_format=application%2Fpdf&type_of_work=Journal+article

Diamond electrochemistry at the nanoscale: A review

Two-dimensional (2D) molybdenum sulfide (MoS2) is an attractive noble-metal-free electrocatalyst for hydrogen evolution (HER) in acids. Tremendous effort has been made to engineer MoS2 catalysts with either more active sites or higher conductivity to enhance their HER activity. However, little attention has been paid to synergistically structural and electronic modulations of MoS2. Herein, 2D hydrogenated graphene (HG) is introduced into MoS2 ultrathin nanosheets for the construction of a highly efficient and stable catalyst for HER. Owing to synergistic modulations of both structural and electronic benefits to MoS2 nanosheets via HG support, such a catalyst has improved conductivity, more accessible catalytic active sites, and moderate hydrogen adsorption energy. On the optimized MoS2/HG hybrid catalyst, HER occurs with an overpotential of 124 mV at 10 mA cm–2, a Tafel slope of 41 mV dec–1, and a stable durability for 24 h continuous operation at 30 mA cm–2 without observable fading. The high performance...

Hydrogen Evolution Reaction on Hybrid Catalysts of Vertical MoS2 Nanosheets and Hydrogenated Graphene

https://onlinelibrary.wiley.com/doi/pdf/10.1002/aenm.202002260

Nianjun Yang

Papers

Conductive diamond: synthesis, properties, and electrochemical applications

Diamond for bio-sensor applications

Diamond electrochemistry at the nanoscale: A review

Hydrogen Evolution Reaction on Hybrid Catalysts of Vertical MoS2 Nanosheets and Hydrogenated Graphene

Ni-Activated Transition Metal Carbides for Efficient Hydrogen Evolution in Acidic and Alkaline Solutions