High Efficiency Epitaxial‐Graphene/Silicon‐Carbide Photocatalyst with Tunable Photocatalytic Activity and Bandgap Narrowing

Abstract

much effort has been devoted to searching for new types of photocatalytic materials for production of hydrogen, as an environment friendly fuel, via water splitting method using solar energy (or through solar water splitting). [ 1 ] In the photocatalytic process, photogenerated electronhole pairs, in a semiconductor material having a suitable bandgap, are responsible for the reduction and oxidation reactions to produce hydrogen and oxygen in conduction band (CB) and valance band (VB), respectively. These charge carriers migrate to the surface of the semiconductor to contribute to a series of specifi c reactions to perform the photocatalytic activity. Along with their important function in hydrogen production from water splitting via solar energy conversion, these photogenerated carriers, the electrons, and holes, play a very crucial role in pollutant degrada-A novel way of tuning photocatalytic activity and bandgap narrowing in epitaxial graphene/silicon carbide (EG/SiC) yields high effi ciency photocatalyst. Graphitization of SiC by high-temperature thermal decomposition method with different annealing time forms sets of EG/SiC composites having different quality of graphene layers, confi rmed by Raman spectroscopy. The Raman intensity ratio of the 2D band to the G band, I 2D / I G , represents a measure of quality and quantity of graphene and heterojunction interface layer between EG and SiC. Experimental results reveal that I 2D / I G plays a crucial role in tuning the bandgap and enhancement of photocatalytic activity of EG/ SiC composites in a systematic manner irrespective of crystal structure or size of the SiC particles. In addition, EG/SiC shows intense broad background absorption in the visible range with increasing I 2D / I G . The suitable selection of I 2D / I G for EG/SiC gives excellent photocatalytic activity under UV light, up to ≈1000% enhancement and remarkable bandgap narrowing, upto 2 eV and even lesser, which is more than ≈30% reduction, relative to the as received SiC. The effi cient control of the electronic structure in such EG/SiC heterojunctions obtained by tailoring the structural parameter I 2D / I G opens up promising pathway for bandgap engineering and enhancement of photocatalytic activity.

Recent progress of heterostructures based on two dimensional materials and wide bandgap semiconductors

“…[110,111] Mathur et al proposed a new method to modulate photocatalytic activity and band gap narrowing in EG/SiC (6H-SiC and 3C-SiC) to produce efficient photocatalysts. [112] The photocatalytic reaction rate for EG/6H-SiC composites were improved by ~1000% under UV light, and the bandgap was narrowed to 2 eV or even smaller under the visible light with a tunable quality factor I2D/IG. The Raman intensity ratio I2D/IG of the 2D band to the G band of graphene played a crucial role in modulating the band gap and enhancing the photocatalytic activity of EG/SiC composites.…”

“…Reproduced with permission. [112] b. Schematic of charge separation in SnO2/3C-SiC NWs. Reproduced with permission.…”

Controllable synthesis of SiC@Graphene core‐shell nanoparticles via fluidized bed chemical vapor deposition

“…7 Until now, the research of SiC@Graphene (SiC@G) coreshell nanoparticles has received immense interest and SiC@G core-shell nanoparticles show great potential as heterojunctions for photocatalysis, additives in engine oil to improve tribology properties, and reinforcing phase of composites. [8][9][10][11] For synthesis strategy, a couple of physical and chemical approaches have been developed to prepare SiC@G coreshell nanoparticles, such as ball milling, thermal treatment, laser irradiation, and chemical vapor deposition (CVD). [12][13][14] A wet ball milling method was proposed to prepare SiC@G core-shell nanoparticles by wrapping SiC nanoparticles with graphene fewer than 6 layers.…”

Flexible Fe3Si/SiC ultrathin hybrid fiber mats with designable microwave absorption performance

“…With ideal mechanical properties, excellent chemical stability, outstanding high temperature resistance and low density, [1][2][3][4][5] silicon carbide (SiC) has been recognized as an ideal candidate for both structural (e.g., composites reinforcement/matrix, 6,7 aero-engine, 3,8 nuclear reactor, [9][10][11] etc.) and functional materials (e.g., electromagnetic wave (EM) absorbers, 12,13 catalyst templates, 14,15 mechanical/gas sensors supporters, 16 etc.) operating in harsh environments.…”

“…and functional materials ( e.g. , electromagnetic wave (EM) absorbers, 12,13 catalyst templates, 14,15 mechanical/gas sensors supporters, 16 etc. ) operating in harsh environments.…”