ABSTRACT
Electrochemical gas evolution and activation reactions are complicated processes, involving not only active electrocatalysts but also the interaction among solid electrodes, electrolyte, and gas-phase products and reactants. In this study, multiphase interfaces of superadsorbing graphene-based electrodes were controlled without changing the active centers to significantly facilitate mass diffusion kinetics for superior performance. The achieved in-depth understanding of how to regulate the interfacial properties to promote the electrochemical performance could provide valuable clues for electrode manufacture and for the design of more active electrocatalysts.
ABSTRACT
The oxygen evolution reaction (OER) is the rate-limiting process for water splitting, and highly efficient large-area OER photoanodes have been considered as an essential part in photoelectrochemical water splitting reactors. The high hole-electron separation efficiency of photoanodes is highly required for real applications of photoanodes in sufficiently harvesting solar energy. Herein we show that the inactive g-C3N4 nanolayers can be self-assembled with BiVO4 into a highly coupled BV/CN dyad to significantly enhance the charge separation efficiency of BiVO4 photoelectrodes for the OER. The incident photon-to-current conversion efficiency (IPCE) of visible light (400 nm) provided by the scalable BV/CN-5 photoanode was estimated to be 50% at 1.23 V vs. RHE in 0.5 M Na2SO4 solution and significantly increased to 97% at a bias voltage of 1.6 V vs. RHE.
ABSTRACT
Superhydrophobic and superhydrophilic surfaces are of great interest because of a large range of applications, for example, as antifogging and self-cleaning coatings, as antibiofouling paints for boats, in metal refining, and for water-oil separation. An aqueous ink based on three-dimensional graphene monoliths (Gr) can be used for constructing both superhydrophobic and superhydrophilic surfaces on arbitrary substrates with different surficial structures from the meso- to the macroscale. The surface wettability of a Gr-coated surface mainly depends on which additional layers (air for a superhydrophobic surface and water for a superhydrophilic surface) are adsorbed on the surface of the graphene sheets. Switching a Gr-coated surface between being superhydrophobic and superhydrophilic can thus be easily achieved by drying and prewetting with ethanol. The Gr-based superhydrophobic membranes or films should have great potential as efficient separators for fast and gravity-driven oil-water separation.
ABSTRACT
The Kirkendall effect was utilized to synthesize mesoporous silicalite-1 zeolite nanocrystals without the involvement of additional templates. The mesopore size as well as the particle size can be easily controlled by nanoscale Kirkendall growth via significantly reducing the amount of water or tetrapropylammonium hydroxide, which were used in large quantities in conventional methods. The Kirkendall growth method is thus suitable for large-scale synthesis of mesoporous MFI zeolites with very high yields but low cost for practical applications.
ABSTRACT
Effective integration of one-dimensional carbon nanofibers (CNF) and two-dimensional carbon sheets into three-dimensional (3D) conductive frameworks is essential for their practical applications as electrode materials. Herein, a novel "vein-leaf"-type 3D complex of carbon nanofibers with nitrogen-doped graphene (NG) was prepared through a simple thermal condensation of urea and bacterial cellulose. During the formation of the 3D complex CNF@NG, the graphene species was tethered to CNF via carbon-carbon bonds. Such an interconnected 3D network facilitates both the electron transfer and mass diffusion for electrochemical reactions.
