西原研究室 Nishihara Lab

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Research

Development of advanced functional carbon materials

It is difficult to precisely control the structure of carbon-based materials with non-crystalline frameworks. Moreover, precise structure drawing of such non-crystalline materials is also a difficult issue. We have developed the new techniques which allow the bottom-up synthesis of advanced carbon materials with controlled structures at atomic/molecular scale, specifically using organic synthesis or chemical-vapor deposition. Thus, a variety of functional carbon materials have been achieved such as metal-carbon frameworks with defined chemical structures like organic crystals, micro/mesoporous materials with singlegraphene walls, and carbon-based composite materials. Also, we focus on the elucidation of physicochemical properties of carbon materials including reactivity, durability, and catalysis from the view point of chemistry by using advanced analysis techniques. Moreover, we proceed in the application of our advanced carbon-based materials for supercapacitors, secondary batteries, fuel cells, heat pump, new energy devices, functional adsorbents, catalysis, and healthcare, with many collaborators including research organizations and companies.

 
 

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Research topics

There are many publications describing "graphene porous materials" and "three-dimensional (3D) graphene materials". However, most of them are materials with stacked graphene walls or materials with macropores rather than micro/mesopores. Our group is working on nanoporous materials with single-graphene walls, namely "single-walled nanoporous graphenes", such as zeolite-templated carbon (ZTC, Fig. 1) and graphene mesosponge (GMS, Fig. 2). These materials possess unique properties such as developed micro/mesopores, oxidation resistance, high conductivity, and mechanical flexibility, and can be distinguished from conventional nanoporous carbons and other graphene-based materials. Thus, they are expected to a variety of applications including supercapacitors, lithium-ion batteries, fuel cells, heat pump, and catalyst supports.

Fig. 1 Structure model of ZTC.
 
Fig. 2 Structure (left) and a TEM photo (right) of GMS.
 

Nanoporous materials with single-graphene walls are mechanically flexible, and they can be reversibly contracted and recovered like plastic sponges. Most of nanoporous materials are mechanically hard, and only a few types of nanoporous materials exhibit a large degree of deformation by mechanical force. We define such elastic nanoporous materials as 'nanosponges', and open the door of new physicochemistry based on the 'hyper nanospace' which can be deformed by mechanical force. For instance, it is possible to induce liquid-gas phase transition by squeezing nanosponges containing liquid (Fig. 3). Thus, the latent heat can be controlled by mechanical force, and this mechanism enables the design of a new type of heat pump.

Fig. 3 Liquid/gas phase transition using nanosponge.
 
Fig. 4 The cooling effect incused by sandwiched nanosponge.
 

Carbon materials are prepared by carbonization of organic precursors. During the carbonization process, the structure of a precursor is greatly changed, resulting in the formation of disordered and amorphous carbon structures. Recently, carbonization of crystalline materials like metal-organic frameworks (MOFs) has been intensively investigated, whereas only amorphous carbons have been synthesized. We have discovered a way to synthesize ordered carbonaceous frameworks (OCFs) which retain the structure regularity as well as molecular blocks of the precursor organic crystal (Fig. 5). OCFs are the hybrid of crystalline materials like MOFs and carbon materials, and we are developing new catalysts including alternatives for platinum catalysts.

Fig. 5 Synthesis scheme of OCFs.
 

We are developing healthcare applications using carbon-based materials. An example is flexible honeycomb monolith with micrometer channels. Honeycomb monoliths which are widely used for car mufflers are produced by extrusion molding, whereas the minimum channel size is restricted to about 200 micrometers. In 2004, Tamon, Mukai, and Nishihara developed a preparation method for honeycomb monoliths with channel sizes of 5 to 200 micrometers, via ice-templating approach. Moreover, Nishihara et al. succeeded in downsizing of channel size to 180 nm. In 2016, Nishihara et al. discovered a distinct structure-directing function of cellulose nanofibers for the microhoneycomb structures, and moreover, honeycomb monoliths with sponge-like flexibility were developed by compositing with graphene. We are developing a variety of healthcare applications using the honeycomb monoliths with micrometer straight channels and mechanical flexibility.

Fig. 6 Comparison of conventional honeycomb monolith and honeycomb monoliths with micrometer-scale channels.
 

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Highlighted research
2022
In-depth analysis of key factors affecting the catalysis of oxidized carbon blacks for cellulose hydrolysis (PDF)
2021
Ru complex and N, P-containing polymers confined within mesoporous hollow carbon spheres for hydrogenation of CO2 to formate (PDF)
2021
Edgeless porous carbon coating for durable and powerful lead-carbon batteries (PDF)
2021
Scalable nanoporous carbon films allow line-of-sight 3D atomic layer deposition of Pt: towards a new generation catalyst layer for PEM fuel cells (PDF)
2021
Synthesis of graphene mesosponge via catalytic methane decomposition on magnesium oxide (PDF)
2021
Force-responsive ordered carbonaceous frameworks synthesized from Ni-porphyrin(PDF)
2021
Lamellar MXene Composite Aerogels with Sandwiched Carbon Nanotubes Enable Stable Lithium-Sulfur Batteries with a High Sulfur Loading (PDF)
2021
A volatile redox mediator boosts the long-cycle performance of lithium-oxygen batteries (PDF)
2021
High-density monolithic pellets of double-sided graphene fragments based on zeolite-templated carbon (PDF)
2021
Elucidation of oxygen reduction reaction and nanostructure of platinum-loaded graphene mesosponge for polymer electrolyte fuel cell electrocatalyst (PDF)
2020
pH-Dependent Morphology Control of Cellulose Nanofiber/Graphene Oxide Cryogels (PDF)
2020
Pyrene‐Thiol‐modified Pd Nanoparticles on Carbon Support: Kinetic Control by Steric Hinderance and Improved Stability by the Catalyst‐Support Interaction (PDF)
2020
Development of a simple NLDFT model for the analysis of adsorption isotherms on zeolite templated carbon (ZTC) (PDF)
2020
Iron porphyrin-derived ordered carbonaceous frameworks (PDF)
2020
Quantifying Carbon Edge Sites on Depressing Hydrogen Evolution Reaction Activity (PDF)
2020
Unusual Redox Behavior of RuthenoceneConfined in the Microporesof Activated Car (PDF)
2019
Effect of carbon surface on degradation of supercapacitors in a negative potential range (PDF)
2019
Force-driven reversible liquid-gas phase transition mediated by elastic nanosponges (PDF)
2019
Insight into the origin of carbon corrosion in positive electrodes of supercapacitors (PDF)
2019
4.4 V supercapacitors based on super-stable mesoporous carbon sheet made of edge-free graphene walls (PDF)
2018
A nacre-like carbon nanotube sheet for high performance Li-polysulfide batteries with high sulfur loading (PDF)
2018
Enhanced hydrogen chemisorption and spillover on non-metallic nickel subnanoclusters (PDF)
2018
Central metal dependent modulation of induced-fit gas uptake in molecular porphyrin solids (PDF)
2017
Beads-Milling of Waste Si Sawdust into High-Performance Nanoflakes for Lithium-Ion Batteries (PDF)
2017
Synthesis of ordered carbonaceous frameworks from organic crystals (PDF)
2017
Graphene-based ordered framework with a diverse range of carbon polygons formed in zeolite nanochannels (PDF)
2017
Graphene-based ordered framework with a diverse range of carbon polygons formed in zeolite nanochannels (PDF)
2016
Remarkable performance improvement of inexpensive ball-milled Si nanoparticles by carbon-coating for Li-ion batteries (PDF)
2016
Oxidation-Resistant and Elastic Mesoporous Carbon with Single-Layer Graphene Walls (PDF)
2016
Cellulose Nanofiber as a Distinct Structure-Directing Agent for Xylem-Like Microhoneycomb Monoliths by Unidirectional Freeze-Drying (PDF)

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Press-release, web articles
2019
Developing a New Type of Refrigeration via Force-Driven Liquid Gas Transition
2019
New materials for high-voltage supercapacitors
2017
カーボンの中に金属が規則配列した触媒 -貴金属に替わる安価な触媒開発を目指して(academist Journal)
2017
A new synthesis route for alternative catalysts of noble metals
2017
Waste silicon sawdust recycled into anode for lithium-ion battery
2016
導電性・耐食性に優れた 大表面積スポンジ状グラフェンの開発に成功 ~ナノ細孔が柔軟に変形~

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