Synthesis of 3C/2H/6H heterojunction SiC nanowires with high-performance supercapacitors by thermal evaporation

In this study, we present a novel approach to enhance the electrochemical energy storage performance of SiC nanowires (SiC NWs) by developing heterostructured SiC NWs with varying contents of 3C-, 2H-, and 6H-SiC using a simple thermal evaporation method. The content of the three SiC crystal phases was regulated by adjusting the raw materials and reaction temperature, and the Rietveld phase analysis was employed to determine their content. The prepared SiC NWs had a mixed structure composed of a 3C-SiC matrix embedded with 2H-SiC and 6H-SiC nanosegments. The conductive network with a high specific surface area promoted the easy penetration of the electrolyte ions. Meanwhile, the heterogeneous structures constructed using 3C-SiC, 2H-SiC, and 6H-SiC nanosegments in SiC NWs exhibited local structural distortion and could promote charge separation. Based on the synergistic effects of the above multiple structures, the electrochemical properties of the SiC NWs were hence improved. When the contents of 3C, 2H, and 6H-SiC in the SiC NWs were 55%, 33%, and 12%, respectively, the specific capacitance at a scanning rate of 10 mV s(-1) was 227.8 F g(-1), which was 2.1 times that of the SiC NWs with 69%, 26%, and 6% of 3C, 2H, and 6H, respectively. In addition, the assembled symmetrical supercapacitor (SC) displayed excellent cycling stability (the retention rate was 90.12% after 10 000 cycles). This study is beneficial for designing SiC NWs with exceptional performance in SC applications.