We present a facile, environment-friendly and mild method to fabricate graphene hydrogel by heating graphene oxide (GO) suspension containing sodium bicarbonate (NaHCO3). This method demonstrates a new type of in situ reduction-assembly approach to construct graphene hydrogel through simultaneous water evaporation and GO reduction. The freeze-dried graphene aerogel (G-Gel) shows excellent adsorptivity to heavy metal ions and dyes. The thermally treated G-Gel (TG-Gel) exhibits promising performance in recyclable selective absorption of oils and organic solvents.

•Pt/3D-G/FTO was prepared by a facile, convenient, inexpensive and green method.•Pt/3D-G/FTO exhibits much enhanced catalytic activity and better stability for MOR.•3D graphene possesses high surface area, large void volume and high conductivity.•The catalytic ability of Pt/3D-G/FTO raised with the deposition potential.•Pt/3D-G/FTO prepared by CV deposition shows the largest methanol oxidation ability.We report a facile, low-cost and green route to fabricate platinum nanoparticle (Pt NP) decorated three-dimensional (3D) graphene assembled on fluorine-doped tin oxide (FTO) electrodes (Pt/3D-G/FTO) with enhanced electrocatalytic activity. The fabrication process was accomplished by preparation of 3D graphene (3D-G/FTO) electrodes through electrochemical reduction of a graphene oxide suspension followed by electrodeposition of Pt NPs onto them. The Pt/3D-G/FTO electrode exhibits much higher catalytic activity and better stability for methanol oxidation compared with the electrodes prepared by electrodeposition of Pt NPs onto two-dimensional graphene sheets substrate (Pt/G/FTO) or bare FTO (Pt/FTO) under the same condition. These enhancements can be attributed to the high surface area, large void volume and high electrical conductivity as well as smaller size of Pt NPs in the hollows of the 3D architecture and a large amount of ridges on it.

Concave palladium nanocrystals are attractive for their superior catalytic ability arising from high densities of atomic steps and kinks. However, it is still a challenge to generate the concave surface, which is not favored by thermodynamics owing to its higher surface energy. In this study, concave palladium nanocubes have been synthesized kinetically in high yield via a facile one-step wet chemical method using sodium ascorbate (NaA) as the reductant in an aqueous solution. This process allows independent control of the average edge length and the surface curvature of the nanocubes, respectively. The particle morphology can be tuned by changing the reducing rate during the reaction. Right bipyramids and 5-fold twinned nanorods with concave surfaces have also been synthesized with two reductants at the different stages or an appropriate amount of ascorbic acid only. Remarkable enhancements in both electrocatalytic activity and stability are observed on concave Pd nanocubes and twinned nanocrystals over conventional Pd nanocrystals with flat surfaces and commercial Pd/C.

CdS nanoparticle-sensitized TiO2 (CdS-TiO2) nanotube arrays are synthesized with a facile one-step electrodeposition technique. In these composited nanostructures, CdS nanoparticles uniformly distribute in the TiO2 nanotubes and partially embed in the shell of TiO2 nanotubes. These structures effectively prevent CdS nanoparticles assembling or clogging the nanotubes and improve the contact area between CdS nanoparticles and the TiO2 shells. Furthermore, the size and distribution density of CdS nanoparticles can be tuned easily by controlling the concentration of electrolyte. Coupling TiO2 nanotubes with CdS nanoparticles extends the optical absorption from ultraviolet into the visible-light region up to 580 nm. An 11-fold enhancement in photoelectrochemical (PEC) activity is observed for CdS-TiO2 nanotube arrays compared with plain TiO2 nanotube arrays. This unique method is also suitable for the synthesis of other narrow band gap semiconductor-sensitized TiO2 nanotubes.

We present a facile, environment-friendly and mild method to fabricate graphene hydrogel by heating graphene oxide (GO) suspension containing sodium bicarbonate (NaHCO3). This method demonstrates a new type of in situ reduction-assembly approach to construct graphene hydrogel through simultaneous water evaporation and GO reduction. The freeze-dried graphene aerogel (G-Gel) shows excellent adsorptivity to heavy metal ions and dyes. The thermally treated G-Gel (TG-Gel) exhibits promising performance in recyclable selective absorption of oils and organic solvents.