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Carbon materials have attracted great attention for their diversified applications in supercapacitors, and different structures of carbon have been reported to exhibit dissimilar electrochemical properties. In the past, activated carbons, carbon nanotubes (CNTs), carbon nanofibers and graphene have been shown to have excellent electrochemical performances, but it still remains a problem on how to improve the capacitance of carbon-based materials effectively from the viewpoint of their giant commercial potential. Noticing that connecting chemical groups to carbon can provide large pseudo-capacitance, we hereby demonstrated that the position of the chemical groups also plays an important role in the pseudo-capacitance. In our work, we synthesized graphene nanoribbon (GNR), graphene oxide (GO) and functional MWCNTs and showed that GNR has larger capacitance (calculated to be 202 F/g at a scan rate of 5 mV/s) and energy density compared to CNTs and GO when using as electrode materials. Furthermore, the supercapacitor device based on as-synthesized GNR exhibits excellent cycle stability and rate capability which evident is potential in high performance supercapacitor. Revealing the source of the capacitance, we found that though GNR has less oxygen-containing groups, it has larger pseudo-capacitance than GO and CNTs due to the remarkable edge-riched structure with high activity in electrochemical reactions. This finding highlights the importance of edge structure in carbon-based pseudo supercapacitor and suggests a new insight for the development of pseudo-capacitance electrode materials.

A facile approach to fabricate low-cost hole-transport-material (HTM)-free perovskite solar cell(PSC) based on commercial P25 nanoparticles and bilayer hybrid carbon electrode under ambient condition is reported. The performance of such HTM-free PSCs are highly dependent on the thickness and morphology of the P25 based TiO 2 electron-transport layer(ETL), which can be adjusted by the amount of ethanol and ethyl cellulose in the paste. After optimization, a power conversion efficiency of 12.48% is obtained, which is enhanced by 20.46% compared with solar cells employing hydrothermal TiO 2 ETL. In addition, PSCs with P25 ETL also exhibit excellent long-term stability together with reduced hysteresis. With advantages of low-cost, high efficiency and facile fabrication process, commercial P25 nanoparticles based PSC is highly potential for future commercialization.