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Abstract: Bacterial cellulose (BC) was used as a raw material to produce freestanding carbon aerogels (CAs). The CAs were further decorated with Ni and MnO2/Ni(OH)2 hybrid via electrodeposition and redox reaction to produce carbon nanofiber networks decorated with electrochemically active metal and metal compounds. The properties of this novel material as supercapacitor electrodes were investigated. The electrochemical performance of the electrodes was examined in 1 M Na2SO4 electrolyte using cyclic voltammetry (CV), cyclic charge-discharge (CCD), and electrochemical impedance spectroscopy (EIS) tests. The results showed that a specific capacitance of 109 F g−1 was achieved at the current density of 1 A g−1. The electrodes could deliver an energy density of 9.4 Wh kg−1 and a power density of 4 KW kg−1 and demonstrated a high cyclability. These results showed great potential of this new material for supercapacitor electrodes. A flexible solid-state supercapacitor prototype was prepared using this material to demonstrate its function as a power source for a LED light. This study provided a new way to use BC as a biobased low-cost material for the fabrication of energy storage devices.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Bubbles evolving from electrode surface are the results of the multi-processes, interfacial mass transfer, chemical reaction, micro fluid flow, etc. In this paper, the investigations on the bubble growth mechanism during photoelectrochemical and electrochemical conversions are carried out. The experimental results show two different growth laws during photoelectrochemical and electrochemical conversions, which are chemical reaction and diffusion controlled respectively, caused by the difference in the effective surface area of the electrode. And mathematical models for bubble growth describing the two effects are established. [ABSTRACT FROM AUTHOR]

In this article we report a facile method to create a polyaniline (PANI) nanorod/carbon nanoparticle (CNP) composite structure that is suitable for supercapacitor use. A network of CNPs was conveniently produced on the surface of a nickel foam by collecting candle soot above a burning candle. The PANI nanorods were then electrochemically deposited on the CNP network, forming a star-like interconnected 3D structure. As a comparison, MnO 2 particles were also deposited on the CNP network to produce a broccoli-like structure. The electrochemical properties of these two composites were examined using cyclic voltammetry, cyclic charge-discharge, and electrochemical impedance spectroscopy. The two electrodes exhibited different electrochemical behaviors: high capacitance at low current densities and marked deterioration at high ones for CNPs/PANI and relatively low but stable capacitance for CNPs/MnO 2 . The reasons for this distinction were discussed based on the structures and material properties of the electrodes. [ABSTRACT FROM AUTHOR]

This paper presents a study on single bubble photogenerated by 376 nm laser light at TiO 2 nanorod-array electrode during photoelectrochemical (PEC) conversion. The surface properties of TiO 2 nanorod-array electrode were investigated at first for a better understanding of the three-phase contact line behavior. The results indicate the light-induced hydrophilic effect of TiO 2 nanorod-array electrode under illumination, which makes bubble tend to be pseudo-sphere shape during attaching on electrode. The experimental investigation on photogenerated bubble at TiO 2 nanorod-array electrode shows that there is a linear relationship between cubic root of time and bubble radius, demonstrating the gas products from the surface reaction transferring into bubble through bubble bottom according to the analysis of the relative size between bubble and effective solid surface. Furthermore, the coupling effects between bubble and irradiance were discussed. The bubble scatter effect on light causes a local light intensity increase at electrode surface area on both sides of bubble, and leads to photocurrent increase especially at small bubble size. While the increase of irradiance causes the parameters of bubble evolution period, dissolved gas concentration for nucleation and departure diameter increase, but leads to bubble evolution rate and incident photon conversion efficiency (IPCE) decrease. These results suggest a lower irradiance is preferred for a higher PEC conversion efficiency from the aspects of IPCE and bubble evolution rate. [ABSTRACT FROM AUTHOR]