Jiawen Ren

Jiawen Ren
George Washington University | GW · Department of Chemistry

doctor of chemistry

About

76
Publications
16,827
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5,207
Citations
Citations since 2016
19 Research Items
3196 Citations
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500

Publications

Publications (76)
Article
The massive release of the greenhouse gas CO2 has resulted in numerous environmental issues. In searching for advanced technologies for CO2 capture/conversions, recent advances in electrochemical reduction of CO2 in molten salts shed a light on potential solutions to CO2 mitigation. Electro-reduction of CO2 in molten salts exhibits features like hi...
Article
Climate change represents one of the most important environmental issues of our time. Due to high levels of anthropogenic CO2 emissions, atmospheric CO2 has for the first time ever exceeded 415 ppm and has increased from 315 ppm in 1950. An annual increase in atmospheric CO2 of ∼2 ppm is equal to a net increase of ∼15.6 billion tons of CO2. The com...
Article
Full-text available
In article number 1900056, Stuart Licht and co‐workers, the first high yield electrosynthesis of carbon nano‐onions (CNOs) by low cost molten carbonate electrolysis is shown. The only reactant, CO2, becomes a useful, valuable resource rather than a greenhouse pollutant as a response to mitigate anthropogenic CO2. The synthesis is achieved by exclud...
Article
Hard carbon becomes a candidate for anode materials due to its rich resources and abundant lithium storage sites. However, amorphous carbon with poor stability and electronic conductivity limits its electrochemical performance. In response, this work synthesizes a sandwich-like porous hard carbon/graphene hybrid (HC/G) with graphene sandwiching the...
Article
A high yield, low energy synthesis of carbon nano‐onions (CNOs) by electrolysis of CO2 in molten carbonate is presented. Carbon nano‐onions are a recently recognized, less studied morphology of carbon nanomaterials consisting of nested concentric carbon spheroids. Previously, a high yield growth of carbon nanotubes by CO2 electrolysis in molten car...
Preprint
The rate of ammonia production by the chemical oxidation of iron, N<sub>2</sub>(from air or as pure nitrogen) and water is studied as a function of (1) iron particle size, (2) iron concentration, (3) temperature, (4) pressureand (5) concentration of the alkaline reaction medium. The reaction meduium consists of an aqueous solution of equal molal co...
Preprint
Full-text available
In the solar thermal electrochemical process (STEP), sunlight is split into visible (for photovoltaic electricity) and thermal (unused, sub-bandgap) radiation using the full solar spectrum to efficiently drive high temperature electrolyzes. Electrolysis conditions for STEP ammonia are investigated. A mixed molten carbonate/hydroxide electrolyte wit...
Article
Full-text available
This SEM, TEM and Raman Spectra and economic calculations data provides a benchmark for carbon nanotubes synthesized via molten electrolyte via the carbon dioxide to carbon nanotube (C2CNT) process useful for comparison to other data on longer length C2CNT wools; specifically: (I) C2CNT electrosynthesis with bare (uncoated) cathodes and without pre...
Article
Full-text available
A climate mitigation comprehensive solution is presented through the first high yield, low energy synthesis of macroscopic length carbon nanotubes (CNT) wool from CO2 by molten carbonate electrolysis, suitable for weaving into carbon composites and textiles. Growing CO2 concentrations, the concurrent climate change and species extinction can be add...
Article
Displaying superior strength, conductivity, flexibility and durability, carbon nanotube (CNT) applications had been limited due to the cost intensive complexities of their synthesis. We present an inexpensive, high-yield and scale-able synthesis of CNTs. We show that common metals act as CNT nucleation sites in molten media to efficiently drive the...
Article
This paper demonstrates a highly favored route for the synthesis of controlled nanostructures at high rate, high yield, and low cost by molten carbonate electrolysis splitting of CO2. We show the wide, portfolio of carbon nanotubes (CNTs) that can be produced by controlling the electrolysis conditions in this one-pot synthesis. For example solid co...
Article
Full-text available
Transformation of carbon dioxide into carbon nanotubes, CNTs, by electrolysis in molten carbonates provides a low cost route to extract and store this greenhouse gas. CNTs are more stable, compact and valuable than fuels or other CO2 conversion products, providing an incentive to remove CO2 for climate mitigation. Previously, solid core carbon nano...
Article
Full-text available
Primary evidence of the direct uptake of atmospheric CO2 and direct transformation into carbon nanotubes, CNTs, is demonstrated through isotopic labeling, and provides a new high yield route to mitigate this greenhouse gas. CO2 is converted directly to CNTs and does not require pre-concentration of the airbone CO2. This C2CNT (CO2 to carbon nanotub...
Article
Full-text available
As the primary culprit of greenhouse effect, carbon dioxide has garnered global attention, and the technologies currently being developed to reduce the emission of CO2 vary widely. In this study, CO2 was electrochemically reduced in various molten mixtures of LiNaK carbonates to carbon nanomaterials. By regulating the electrolysis current density,...
Article
This is a Density Functional Theory (DFT) study on the influence of an alloying mixture of Ni-Zn catalysis on carbon nanotube, CNT, growth. The study is inspired by the one pot synthesis of carbon nanofiber during the electrolysis of Li2CO3. Unlike CVD, CNT growth initiates at the liquid/solid, rather than gas/solid interface in the above process....
Article
Full-text available
The cost and practicality of greenhouse gas removal processes, which are critical for environmental sustainability, pivot on high-value secondary applications derived from carbon capture and conversion techniques. Using the solar thermal electrochemical process (STEP), ambient CO2 captured in molten lithiated carbonates leads to the production of c...
Article
Nickel (II) sulfide (NiS) nanosheets with a thickness of 10 nm and a size of 200 nm were facilely grown on stainless steel (SLS) meshes via a one-pot hydrothermal method. This unique construction renders an excellent electrical contact between the porous film of active NiS sheets and the highly conductive substrate, which exhibits a superior cataly...
Article
Full-text available
One pathway to remove the greenhouse gas carbon dioxide to mitigate climate change is by dissolution and electrolysis in molten carbonate to produce stable, solid carbon. This study determines critical knowledge to minimize the required electrolysis energy, the reaction stoichiometry in which carbon and O2 are the principal products, and that CO2 c...
Article
An ionothermal sol–gel strategy to synthesize hierarchically porous carbon aerogels doped with different heteroatoms is presented by using biomass precursors in a scalable process. Morphologically similar but chemically different materials are used to study the influence of heteroatoms in Li–S batteries. The materials show capacities as high as 129...
Article
Full-text available
Carbon nanofibers, CNFs, due to their superior strength, conductivity, flexibility and durability have great potential as a material resource, but still have limited use due to the cost intensive complexities of their synthesis. Herein, we report the high-yield and scale-able electrolytic conversion of atmospheric CO2 dissolved in molten carbonates...
Article
The production of cement (primarily lime, sand, and water) is a massive, global source of carbon dioxide emissions. Lime is formed through heating limestone (CaCO 3 ), which splits it to CaO and CO 2 . We’ve introduced a carbon dioxide-free replacement methodology, STEP cement, in which limestone is converted to lime and graphite (and no CO 2 ). ST...
Article
Full-text available
This study introduces the high yield, electrolytic synthesis of carbon nanofibers, CNFs, directly from carbon dioxide. Production of a precious commodity such as CNFs from atmospheric carbon dioxide provides impetus to limit this greenhouse gas and mitigate the rate of climate change. CNFs are formed at high rate using inexpensive nickel and steel...
Article
In article number 1401660, Tim-Patrick Fellinger and co-workers show that it is possible to make highly active and cheap catalysts using an easy-to-do recipe. The cover image illustrates that rain splits at the interface of gemstones and carbonized paper. This indicates the symbiotic interaction of nickel oxide nanoparticles and nitrogen-doped carb...
Article
Nitrogen-doped carbon-based catalysts are promising candidates to substitute expensive and moderately durable platinum-based catalysts for polymer electrolyte membrane fuel cells (PEMFCs). Condensation of ionic liquids (ILs) in salt melts enables the formation of hierarchically porous nitrogen-doped carbons with very high surface areas. Here we pre...
Article
An efficient water splitting electrocatalyst is presented. Cheap and sustainable cellulose filter paper, infiltrated with nickel acetate as the nickel source, and phenanthroline as a ligand and nitrogen source are carbonized together. Nitrogen functionalities turn out to be crucial coordination sites for the supported Ni/NiO(OH) particles. This sim...
Article
A new type of sulfonated carbon material with amphiphilic properties was synthesized by the hydrothermal carbonization of a mixture of furfural–sodium dodecylbenzene sulfonate at 180 °C in an autoclave. The addition of SDBS is necessary for the production of materials with long carbon chains and is possibly used to improve the solubilization of lon...
Article
The sole presence of relatively small micropores in zeolite catalysts strongly influences the mass transfer and catalytic conversion of bulky molecules. Herein, we report a novel synthesis route for the confined synthesis of hierarchical MFI zeolite microspheres with nanorod oriented-assembled structures for the first time via the hydrothermal crys...
Article
Conversion of carbohydrates to 5-hydroxymethylfurfural (HMF) will provide a new step toward achieving renewable biomass-based chemicals and fuels platform. Recently, the excellent yield of HMF (91.0%) in dimethyl sulfoxide (DMSO) catalyzed by sulfonated carbon was demonstrated, but the separation of HMF from the reaction mixture remains challenging...
Article
Highly stable hierarchical ZSM-5 zeolites with intra-crystalline mesopores and inter-crystalline macropores have been synthesized via a steam-assisted conversion in the presence of polyethylene glycol. XRD, SEM, TEM, N2 sorption and mercury intrusion measurement revealed that the irregular intra-crystal mesopores (2–10 nm) in each zeolite nanocryst...
Article
A novel mesoporous niobium phosphate supported Ruthenium (Ru/NbOPO4) catalyst was prepared for the selective conversion of cellulose to sorbitol. In this study, the influence of reaction temperature, hydrogen pressure, reaction time and the amounts of Ru loading was systematically investigated. The results showed that high yield of sorbitol about 5...
Article
Hollow zeolite microspheres have been hydrothermally synthesized in the presence of organosilanes via a dissolution–recrystallization procedure. In the presence of organosilanes, zeolite particles with a core/shell structure formed at the first stage of hydrothermal treatment, then the core was consumed and recrystallized into zeolite framework to...
Article
By using cetyltrimethylammonium bromide (CTAB) as the template, a series of mesoporous niobium phosphates were synthesized at different pH values in an aqueous solution. Techniques such as small-angle X-ray diffraction, transmission electron microscopy (TEM) and N2 sorption technique were employed to characterize the mesoporous structures of thus-s...
Article
Well-defined superparamagnetic Fe3O4/SiO2/polyaniline (PANi) core–shell–shell microspheres with smooth surface are synthesized as the first time. Fe3O4/SiO2 core–shell microspheres modified by poly(vinylpyrrolidone) (PVP) are coated with PANi through in situ polymerization of aniline monomers in ethanol dispersion. Low polymerization temperature is...
Article
5-Hydroxymethylfurfural (HMF) is a very important intermediate in the fine chemical industry. This study aims to investigate the direct conversion of glucose or glucose-based carbohydrates, such as sucrose, cellobiose, inulin, starch and cellulose, to HMF by using a Sn-Mont catalyst. With the use of this catalyst, a HMF yield of 53.5% was achieved...
Article
A Ni-B amorphous alloy catalyst (AP Ni) was prepared and used in an aqueous-phase reforming (APR) of glycerol. Higher stability and higher selectivity towards H2 were obtained when compared with Raney Ni. After 130 h’ on stream aqueous-phase reforming of glycerol, the amorphous Ni-B catalyst was transformed to hexagonal closed-packed (hcp) Ni cryst...
Article
Full-text available
Activated carbon-based carbon/carbonaceous composites with different surface functional groups were synthesized by a hydrothermal carbonization-deposition method in which commercial activated carbon was exposed to a gaseous mixture of furfural/water or furfural/acrylic acid/water at 180 °C to form the carbon/carbonaceous composites. The products we...
Article
Full-text available
The hexagonal close-packed (hcp) Ni nanoparticles have been synthesized successfully in triethylene glycol with high ionic Ni concentration under the presence of protective agent (PVP or PEG). The protective agent (PVP or PEG) played an important role in the formation of hcp Ni. The crystal structure of nickel can be tuned by changing the concentra...
Article
Mesoporous zeolite (silicalite-1, ZSM-5, TS-1) single crystals have been successfully synthesized by adding soluble starch or sodium carboxymethyl cellulose (CMC) to a conventional zeolite synthesis system. The obtained samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microsco...
Article
In this paper, extremely hydrothermal stable mesoporous Al-SBA-15 with controllable Al content has been synthesized by using triblock copolymer (P123) as template under an assistance of NaF at 160 °C. This kind of material was characterized by powder X-ray diffraction (XRD), N2 sorption isotherms, transmission electron microscopy (TEM), 27Al MAS NM...
Article
A novel mesoporous Co–Al spinel catalyst with high surface area and suitable basicity was prepared by the thermal decomposition of Co–Al hydrotalcite-like compound. The properties of the solid base catalyst were characterized by XRD, FTIR, TEM, nitrogen sorption and CO2-TPD. The formation mechanism of the mesopores and the Co–Al spinel structure wa...
Article
Full-text available
The electromagnetic and microwave absorbing properties of nickel ferrite nanocrystals were investigated for the first time. There were two frequencies corresponding to the maximum reflection loss in a wide thickness range from 3.0 to 5.0 mm, which may be bought by the nanosize effect and the good crystallization of the nanocrystals.
Article
Three-dimensional nanoflowers consisting of uniform crystalline SnO2 nanorods were spontaneously grown by the gradual hydrolysis of SnS32− in an aqueous system at 180°C. The resulting material was characterized by using SEM, TEM, EDX, SAED, XRD, and UV–vis techniques. The results clearly show that these uniform crystalline SnO2 nanorods grow in the...
Article
The carbonaceous monoliths rich in surface sulfonic acid groups were synthesized by one-pot hydrothermal carbonization of the mixture of p-toluenesulfonic acid/glucose/resorcinol at 180°C. The Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy characterizations confirmed the presence of surface sulfonic groups on these mon...
Article
Hermetically-sealed graphite encapsulated cobalt core/shell nanostructures have been prepared by the CO Boudouard reaction using in situ generated cobalt as the catalyst. Only core/shell nanostructures were obtained, rather than a mixture of cobalt nanoparticles with carbon nanotubes or nanofibers. The magnetic cobalt nanoparticles are highly cryst...
Article
A new strategy was developed for the direct conversion of furfural to 1,5-pentanediol by the hydrogenolysis of the furan ring under mild conditions based on Pt/Co(2)AlO(4) catalyst. This is the first report of the direct catalytic conversion of furfural to 1,5-pentanediol with high yield.
Article
A novel carbon-based solid acid, which was prepared by a facile and eco-friendly approach from glucose and p-toluenesulfonic acid (TsOH), was used to catalyze fructose dehydration into 5-hydroxymethylfurfural (HMF) for the first time and exhibits excellent catalytic performance. As high as 91.2% yield of HMF was achieved in dimethyl sulfoxide (DMSO...
Article
Mesoporous carbon materials with partially graphitized structure were synthesized by a one-pot, co-assembly of tri-block copolymer with phenolic resin under the assistance of ammonium ferric citrate. The structure was characterized by XRD, TEM, N2 sorption and TG/DTA. The mesoporous structure of the polymer conserved after the addition of ammonium...
Article
Hydrothermally highly stable mesoporous aluminosilicate spheres with radial channels were synthesized in the CTAB–NaF–TPAOH system through a one-step procedure at high aging temperature. The characterization by transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogenadsorption/desorption analysis, 27Al MAS solid state NMR spectrosc...
Article
The superparamagnetic Fe3O4 microspheres about 300 nm diameter were prepared by the solvothermal method. After treated with chlorohydric acid, it was coated with aminopropyl-functionalized amorphous silica by the condensation of tetraethylorthosilicate (TEOS) and γ-aminopropyltriethoxysilane (APTES) through Stöber modified method. FT-IR, elemental...
Article
A novel mesoporous Pd/cobalt aluminate bifunctional catalyst has been synthesized by a facile co-precipitation process and used in aldol condensation of furfural with acetone and the following hydrogenation of condensation products. This kind of bifunctional catalyst has good activity and can be recycled and regenerated easily.
Article
CO disproportionation produces carbon deposits that cover active sites and induce catalyst deactivation. However, understanding of this detrimental reaction on reduced ceria is deficient. Herein, the reversibility and reaction mechanism of CO disproportionation on reduced ceria are investigated. The reversibility of the CO disproportionation was st...
Article
A novel carbon-based solid-acid catalyst was simply prepared for the first time by the thermal treatment of p-toluenesulfonic acid (TsOH) with d-glucose at 180°C in a sealed autoclave and it was proved to have high acidity and to be a highly efficient solid-acid catalyst in the reactions such as esterification of succinic acid with ethanol.
Article
In this work, novel three-dimensional (3D) navicular ceria micro/nanocomposite architecture with multi-layered structure was synthesized for the first time via solution reaction followed by a simple hydrothermal treatment in the presence of lysozyme. During the synthesis procedure, a 3D navicular ceria precursor (Ce2O(CO3)2·H2O) with multi-layered...
Article
Full-text available
A simple and inexpensive approach to synthesizing mesoporous Fe3O4 is developed by using citric acid-assisted solid thermal decomposition of ferric nitrate. The structure and magnetic property of mesoporous Fe3O4 were characterized by XRD, FT–IR, N2 adsorption–desorption isotherms, TEM, and vibrating sample magnetometer. It was shown that the decom...
Article
Nearly mono-dispersed nickel ferrite nanoparticles have been synthesized by a solid-liquid interface reaction of Ni2+Fe23+–oleate complex with alkali solution assisted by hydrothermal crystallization. Chemical reactions took place at the interface of the solid and liquid phase and the generated particles were then dispersed into the aqueous solutio...
Article
Recently, extensive works have been devoted to the morphology control of mesoporous materials with respect to their use in various applications. In this paper, we used two kinds of mesoporous silica, SBA-15 rods and spheres as hard templates to synthesize morphology-controllable mesoporous metal oxides. By carefully controlling the loading of metal...
Article
Full-text available
Wormhole-like mesostructured polyaniline (PANi) has been synthesized by using sodium dodecyl benzene sulfonate (SDBS) as a structure directing agent and iron trichloride (FeCl3 · 6H2O) or ammonium persulfatee (APS, (NH4)2S2O8) as an oxidant in an acidic solution. The formation mechanism and structure of polyaniline was studied by powder X-ray diffr...
Article
Monodispersed SBA-15 rods with different lengths (from hexagonal platelets to short rods, and to longer rods) have been synthesized by using triblock copolymer P123 as a structure-directing agent and glycerol as a cosolvent. Our studies showed that glycerol is indispensable for tuning the length of SBA-15 rods. And, in the presence of glycerol, the...
Article
Nanosized multilayered silica vesicles have been synthesized through a dual-template way by using cetyltrimethylammonium bromide (CTAB) and C3F7O(CFCF3CF2O)2CFCF3 CONH(CH2)3N+(C2H5)2CH3I− (FC-4) as the cotemplates and tetraethyl orthosilicate (TEOS) as the siliceous precursor. According to transmission electron microscopy, X-ray diffraction, and N2...
Article
MFI nanozeolite microspheres with intercrystal mesopores were synthesized by a steam-assisted crystallization–aggregation method, starting with close packed amorphous SiO2 or Al-containing SiO2 colloidal nanoparticles. The obtained samples with different Si/Al ratios were characterized by X-ray diffraction, Fourier transform infrared spectroscopy,...
Conference Paper
Carbons with well defined porous structures are synthesized using different types of mesoporous silcas as templates. The silica templates include SBA-15, SBA-16, FDU-12, and M41S, leading to carbon structures with different pore size and distribution corresponding to the templates. These carbons are used as supports for platinum-ruthenium nanoparti...
Article
On the basis of a sol-gel process, a facile, low cost, and one-step approach for preparing ordered magnetic mesoporous gamma-Fe(2)O(3)/SiO(2) nanocomposites by an evaporation-induced self-assembly (EISA) approach is presented. Various mesostructured silica materials (P6mm or Im3m) incorporated with different amounts of iron oxide (n(Si)/n(Fe) = 9/1...
Article
Ordered mesoporous LaCoO3 perovskite with high surface area was synthesized via nanocasting strategy by using ordered mesoporous cubic (Ia3d) vinyl silica as the template. The sample, prepared by filling mesopores in silica template with a La−Co citrate complex precursor followed by calcination and silica removal, was characterized by XRD, TEM, and...
Article
In this paper, a series of ordered mesoporous single-crystal Cr2O3 samples were synthesized through a hard-templating pathway by using three-dimensional (3D) cubic mesoporous silica, KIT-6, as the template and chromium nitrate as the precursor. In the synthesis, the intermediate composites (chromium nitrate/KIT-6) were calcined in air for 4 h at di...
Article
A mesoporous carbon structure was template-synthesized from small nanoparticles of silica with internal M41S type mesopores. The silica template was synthesized according to Suzuki et al. using an ionic surfactant to create the internal mesopores 1.8−3.5 nm diameter and a nonionic surfactant to limit the overall size of the particle. Larger mesopor...
Article
A method to prepare supported nanoparticles of Pt–WO3 with composition control in nanoscales is presented. Transmission electron microscopy shows crystal domains in the nanoparticles, which have a narrow size distribution. Energy dispersive X-ray analyses performed in different regions show good uniformity in the Pt : W ratio, which correlates line...
Article
This work discusses the preparation of small metal nanoclusters stabilized with glycol and OH−1, which are attractable building blocks for the fabrication of new heterogeneous catalyst. New Os and Pt/Rh bimetallic nanoclusters with small particle size and narrow size distribution have been prepared by the polyol synthesis method and characterized b...