Controllable conversion of rice husks to Si/C and SiC/C composites in molten salts

Pang, Daijun; Weng, Wei; Zhou, Jing; Gu, Dong; Xiao, Wei

doi:10.1016/j.jechem.2020.06.072

Cited by 35 publications

(20 citation statements)

References 45 publications

(91 reference statements)

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“…Fe, Fe 3 C and carbon are detected in the X‐ray diffraction (XRD) pattern and Raman spectrum of Fe/Fe 3 C‐MC (Supporting Information, Figure S1). The CO 2 ‐derived carbon (denoted as CDC) obtained by the electrolysis of CO 2 alone shows lower graphitization due to the absence of metallic nuclei to catalyze graphitization [12] . Iron contents in the electrolytic samples without (denoted as Fe‐C) and with (that is, Fe/Fe 3 C‐MC) the acid leaching are calculated as 68.1 and 2.4 wt % (Supporting Information, Figure S2).…”

Section: Figurementioning

confidence: 99%

Electrochemical Reduction of Carbon Dioxide and Iron Oxide in Molten Salts to Fe/Fe₃C Modified Carbon for Electrocatalytic Oxygen Evolution

et al. 2020

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Non-noble electrocatalyst for the oxygen evolution reaction (OER) is essential for water electrolysis and electrochemical conversion of CO 2. Integrating electrochemical fixation of CO 2 and electrochemical metallurgy to prepare advanced OER electrocatalyst is a promising solution to promote carbon neutrality and renewable energy. Herein, the electrochemical reduction of CO 2 and Fe 2 O 3 are combined in molten salts to prepare cathodic Fe 3 C-based electrocatalyst and anodic oxygen at 600 8C with enhanced current efficiency. The resulting Fe 3 C-based electrocatalyst outperforms precious electrocatalyst towards the OER operation in 1 M KOH due to a dynamic structural evolution to form an interface of Fe 3 C-FeOOH. The splitting of water and the conversion of CO 2 by electrochemical routes have been regarded as promising strategies to relieve concerns on energy and environmental sustainability. [1-3] The both processes are restricted by the oxygen evolution reaction (OER), which is sluggish in reaction kinetics owing to the four-electron-transfer characteristics. [3] Noble-metal-based catalysts such as ruthenium oxide and iridium oxide possess high activity for OER, but the high cost and scarcity of noble metals limit the large-scale application. Developing high-activity non-noble catalysts for OER is hence of importance. An OER catalyst is expected to possess optimal surface chemistry to ensure active centers with high intrinsic activity, and rationally designed architecture to endow the full exposure of active sites. [1] Iron-based oxides, hydroxides, phosphides, and carbides have widely been explored as nonprecious OER catalysts. [4, 5] In particular, iron carbides with [*] X.

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Section: Figurementioning

confidence: 99%

Electrochemical Reduction of Carbon Dioxide and Iron Oxide in Molten Salts to Fe/Fe₃C Modified Carbon for Electrocatalytic Oxygen Evolution

et al. 2020

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“…[ 6 ] The wide electrochemical window of molten salt electrolytes promises a high current efficiency of the electrochemical reduction of CO 2 in molten salts. [ 6,20–24 ] The high‐temperature environment of inorganic molten salts brings about enhanced mass transfer and facilitated reaction kinetics, enabling an appealing conversion rate of CO 2 free of any precious catalysts. [ 6,14,15 ] Molten salts possess a high heat capacity, which means the heat required by the molten salt fixation of CO 2 can be supplied by solar‐thermal systems.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Fixation of Carbon Dioxide in Molten Salts on Liquid Zinc Cathode to Zinc@Graphitic Carbon Spheres for Enhanced Energy Storage

Xiao

Weng

et al. 2020

Advanced Energy Materials

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to epoxides is realized in ionic liquids by Sun and co-workers. [14,15] Fixation and utilization of CO 2 is also elaborately explored via designing the metal-CO 2 batteries by Ding and co-workers. [16] Fixation of CO 2 into functional carbonaceous materials by capture and electrochemical reduction of CO 2 in molten salts has many advantages. [6,17-19] CO 2 shows a high solubility in molten salts, guaranteeing a highflux uptake rate for a direct and deep removal of CO 2 from atmosphere and industrial flue gas. [6] The wide electrochemical window of molten salt electrolytes promises a high current efficiency of the electrochemical reduction of CO 2 in molten salts. [6,20-24] The high-temperature environment of inorganic molten salts brings about enhanced mass transfer and facilitated reaction kinetics, enabling an appealing conversion rate of CO 2 free of any precious catalysts. [6,14,15] Molten salts possess a high heat capacity, which means the heat required by the molten salt fixation of CO 2 can be supplied by solar-thermal systems. [17] The decomposition voltage of CO 2-capture-generated CO 3 2− in molten salts is lower than 2.0 V (1.3 V for Li 2 CO 3 , 1.6 V for Na 2 CO 3 , and 1.8 V for K 2 CO 3 at 500 °C), therefore the electricity for the conversion of CO 2 in molten salts can be supplied by solar photovoltaic systems. [17] Finally, oxygen in CO 2 can simultaneously be released as anodic O 2 , which is of prime implications on future colony on Mars. [6] One of the major challenges for the electrochemical fixation of CO 2 in molten salts is the insufficient functionality of the deposited carbon on cathode. [6] Amorphous and disordered carbon is commonly obtained by electrochemical conversion of CO 2 in molten salts, which contradicts with the demands of application devices for carbonaceous materials with high graphitization degree. [6] For example, aluminum-ion (Al-ion) battery (AIB) possesses the merits of low cost, high volumetric capacity, and high safety. Many cathode materials are reported for Al-ion batteries, including carbon-based materials, metal sulfides, and V 2 O 5. [25-27] For carbon-based materials, the carbon with higher graphitization degree commonly possesses better performance for reversible Al storage. [26,27] In this regard, pioneering works were conducted by Lu and coworkers. [7,28-33] In their strategy, a highly porous 3D graphene foam is used as the cathode for rechargeable Al-ion batteries,

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“…Molten-salt electrolysis is an efficient method to prepare metals/alloys through the electrochemical reduction of solid oxides. − Silicon with various nanostructures and morphologies (e.g., Si particles, , nanowires, films , ) has been successfully synthesized by rationally modifying reaction conditions, including molten-salt composition, reduction potentials, and raw materials (SiO 2 , CaSiO 3 , ). Among various silica staring materials, bio-SiO 2 possessing unique nanostructures and abundance in nature has attracted tremendous attention, which widely exists in nature plants such as rice husk, − bamboo, and reed plant . In addition, bio-SiO 2 naturally grows with organic components that can be easily converted to C–SiO 2 composite feedstock through pyrolysis.…”

Section: Introductionmentioning

confidence: 99%

Harvesting Si Nanostructures and C–Si Composites by Paired Electrolysis in Molten Salt: Implications for Lithium Storage

Zhao

Cai

Zhao

et al. 2022

ACS Appl. Nano Mater.

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Electrolysis of SiO 2 to produce Si in MgCl 2 -based molten salt faces the challenge of generating chlorine gas at a graphite anode. Herein, we replace the graphite anode with a Mg 2 Si alloy anode that is paired with a C−SiO 2 cathode in molten NaCl−KCl−MgCl 2 . During the paired electrolysis, the Mg 2 Si anode releases two Mg 2+ ions into the electrolyte, resulting in Si nanostructures, while the C−SiO 2 cathode is reduced to C−Si composites without generating SiC. Thus, both electrode reactions obtain desired products, which eliminates chlorine gas evolution and tailors the structure and composition of Si. In addition, the electrolytic Si nanostructures and C−Si composites show enhanced lithium-storage performances. The anodic Si nanostructures display a high initial Coulombic efficiency of 82.7% and achieve a cycling capacity of 1490 mAh g −1 300 cycles later under 2 A g −1 . The cathodic C−Si composite that remains inside the carbon matrix derived from rice husks maintains a stable capacity of 780 mAh g −1 and 92.1% capacity retention after 200 cycles at 0.5 A g −1 . In addition to Si-based anode materials, this study offers an economical and green paired electrolysis approach to preparing various functional materials.

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Controllable conversion of rice husks to Si/C and SiC/C composites in molten salts

Cited by 35 publications

References 45 publications

Electrochemical Reduction of Carbon Dioxide and Iron Oxide in Molten Salts to Fe/Fe₃C Modified Carbon for Electrocatalytic Oxygen Evolution

Electrochemical Reduction of Carbon Dioxide and Iron Oxide in Molten Salts to Fe/Fe₃C Modified Carbon for Electrocatalytic Oxygen Evolution

Electrochemical Fixation of Carbon Dioxide in Molten Salts on Liquid Zinc Cathode to Zinc@Graphitic Carbon Spheres for Enhanced Energy Storage

Harvesting Si Nanostructures and C–Si Composites by Paired Electrolysis in Molten Salt: Implications for Lithium Storage

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Controllable conversion of rice husks to Si/C and SiC/C composites in molten salts

Cited by 35 publications

References 45 publications

Electrochemical Reduction of Carbon Dioxide and Iron Oxide in Molten Salts to Fe/Fe3C Modified Carbon for Electrocatalytic Oxygen Evolution

Electrochemical Reduction of Carbon Dioxide and Iron Oxide in Molten Salts to Fe/Fe3C Modified Carbon for Electrocatalytic Oxygen Evolution

Electrochemical Fixation of Carbon Dioxide in Molten Salts on Liquid Zinc Cathode to Zinc@Graphitic Carbon Spheres for Enhanced Energy Storage

Harvesting Si Nanostructures and C–Si Composites by Paired Electrolysis in Molten Salt: Implications for Lithium Storage

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Electrochemical Reduction of Carbon Dioxide and Iron Oxide in Molten Salts to Fe/Fe₃C Modified Carbon for Electrocatalytic Oxygen Evolution

Electrochemical Reduction of Carbon Dioxide and Iron Oxide in Molten Salts to Fe/Fe₃C Modified Carbon for Electrocatalytic Oxygen Evolution