Direct Conversion of Rice Husks to Nanostructured SiC/C for CO₂ Photoreduction

Abstract

A one‐step and template‐free synthesis of a SiC nanowires/C (SiC‐NW/C) composite from rice husks (RHs) is realized via a molten‐salt‐assisted electrochemical method. The process integrates simultaneously carbonization, electrodeoxidation, nanostructuring, and self‐purification for converting RHs to a SiC‐NW/C hybrid that is assembled from SiC NWs embedded in porous N‐doped graphitic carbon with strong coupling. The SiC‐NW/C nanostructure enables efficient CO2 adsorption and fast separation and transfer of charge carriers. Benefiting from the structural and compositional merits, the SiC‐NW/C composite shows superior activity for photoreduction of CO2 to CO, in the absence of any additional cocatalysts or sacrificial agents. The process proposed herein might help to bridge a closed‐loop carbon cycle in the whole production–utilization of biomass.

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

“…The interplanar distances of 3.4 Å in the shell and 2.1 Å in the core in the high-resolution TEM image ( Figure 2h) are ascribed to the crystal planes of graphitic carbon (002) and Zn (101). [22,35,36] The elements distributions also validate the core-shell Zn@C structure, as confirmed by the separated location of Zn in the core (Figure 2i-k) and carbon in the shell (Figure 2i,j,l). The obtained core-shell Zn@C features a specific surface area of 160 m 3 g −1 and a pore size centered at 4 nm ( Figure S1, Supporting Information).…”

“…The G band in Raman spectrum is the common feature of graphitic materials while D band is the indicator of defects in graphitic carbon. [ 22 ] The stronger G peak than that of D peak in the Raman spectrum of Zn@C also suggests the graphitization (red line in Figure 2b). The core–shell morphology is certified by the field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) results.…”

“…Potentiostatic electrolysis was conducted at −0.9 V versus Ag/Ag 2 SO 4 for 3 h in the Li 2 CO 3 –Na 2 CO 3 –K 2 CO 3 molten salt at 450 °C, with the liquid Zn as the working electrode (cathode) and a platinum‐coated titanium plate as the counter electrode (anode). The X‐ray diffraction (XRD) pattern (red line in Figure 2 a), Raman spectrum (red line in Figure 2b and inset in Figure 2b), and X‐ray photoelectron spectrometer (XPS) spectra (see Zn 2p spectrum in the left side and C ls spectrum in the right side of Figure 2c) all prove the coexistence of Zn and C in the cathodic Zn@C. [ 22,35,36 ] In Figure 2a, the broad peak located at 23° is ascribed to the (002) crystal plane of graphitized carbon (JCPDS No. 01‐0646).…”

“…[ 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.…”

Initial Electrode Kinetics of Anion Intercalation and De‐intercalation in Nonaqueous Al‐Graphite Batteries†

“…With the increasing demand of electrical grid systems and electronic products, development of novel energy storage devices has been considered as the urgent issues, with perspectives in low cost, long‐term operation, safety, broad‐temperature service, etc . [ 1‐7 ] Among the potential systems, nonaqueous Al batteries, [ 8‐12 ] typically the Al‐graphite prototypes, are recently receiving growing attention because of the advantages for well meeting the urgent requirements. According to the current progresses, utilization of Al negative electrodes and graphite positive electrodes has massively decreased the cost of the active materials in the Al batteries.…”