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Composite aerogels with a metallic Ag phase and a semiconductor CeO2 phase are prepared using a conventional epoxide assistant sol–gel method and ethanol supercritical drying. In such an aerogel, CeO2 nanoparticles surround Ag nanoparticles to form a continuous network for mass and charge transfer. The photocatalytic CO2 reduction reaction is studied on the gas–solid interface of the composite aerogels. It is found that with the Ag additives, the activity of the composite aerogels is greatly improved compared with that of pristine CeO2, both under the full-spectrum light and visible light. A high CH4 yield up to 21.9 μmol/g/h and high selectivity can be simultaneously achieved in a composite aerogel containing ∼5 wt.% Ag. Such an enhancement is attributed to the surface plasmon resonance effect brought by Ag, which promotes charge generation and separation efficiency in the composite aerogel.

Transition-metal selenides based materials have recently aroused an increasing consideration in the field of energy reservation and conversion owing to their good electrochemical performance and low synthetic cost. Herein, multi-walled carbon nanotubes supported binary nickel cobalt selenide composite (NiÀ CoÀ Se/CNT) was prepared by a one-pot-hydrothermal method using hydrazine ions that enables the selenium to diffuse and react with the Ni-and Co-cations to form NiÀ CoÀ Se with a stable nanostructure onto the outer walls of the CNT platforms due to the coordination interaction between the metallic cations and surface oxygen-containing group of the conductive scaffolds. The electrochemical performances for urea oxidation reaction (UOR) are accessed in an alkaline medium by cyclic voltammetry (CV), chronopotentiometry (CA), and electrochemical impedancespectroscopy (EIS) tests. The asprepared NiÀ CoÀ Se/CNT hybrid presents an excellent electrocatalytic activity in terms of current density and onset potential due to synergistic effects of tubular CNT scaffolds, additional Co active sites, and electrochemically active NiOOH layer. The CNTs support markedly enhanced the electrocatalytic properties by providing a rapid mass transport for UOR because of their porous network architectures with a robust adhesion to the NiÀ CoÀ Se nanocrystals. Thus, the synthetic methodology synthetic methodology adopted here is entirely effective for constructing various metal selenide compounds in future.

Urea has shown a potential importance as a possible alternative hydrogen-storage source for low-temperature fuel cells. Besides, the electrooxidation of urea provides an efficient solution for the disposal of wastewater in the agricultural industry, but the state-of-the art urea electrocatalysis suffers from the associated sluggish kinetics. In this study, we fabricated unique vertically aligned nanorod arrays-like carbon anchored nickel-cobalt carbonate hydroxides (CÀ NiCo CHs) without agglomeration through a mass scale one-step hydrothermal approach for electrocatalytic oxidation of urea in an alkaline environment. The composite affords a high specific surface area of 162.55 m 2 g À 1 with distinctive porous features, suggesting a large surface exposure and sufficient electrolyte accessibility during chemical reactions. The catalyst exhibits an outstanding electrocatalytic activity towards urea electrooxidation with a high current density and an outstanding durability benefiting from the tuned electric conductivity. Impressively, the hybrid shows a greatly improved catalytic performance at higher KOH moieties with a much-enhanced peak current and a negatively shifted onset voltage, which can be interpreted by the intensive Ni activation processes caused by the densely formed OH À ions. These findings signify that the well-developed nanoarchitecture of CÀ NiCo CHs hybrid could pave the way to rationally fabricate highly active electrocatalysts for urea electrocatalysis.[a] Dr.