ZnO nanorods with a diameter of 25 nm have been synthesized on carbon cloth (CC) by combining atomic layer deposition (ALD) and hydrothermal methods. Platinum nanoparticles were then deposited on photoinduced hydrophilic surface of ZnO nanorods by ALD. Electrochemical performance of the nanocomposite catalyst (Pt@ZnO@CC) for methanol oxidation with or without UV irradiation was evaluated. According to the X-ray photoelectron spectroscopic (XPS) analysis, the surface of ZnO nanorods rich in hydroxide species was more favorable for removal of CO via the so-called bifunctional mechanism. Additionally, the XPS study indicates that the charge transfer occurs between the ZnO nanorods and the Pt nanoparticles. UV light irradiation on the catalyst surface increases the chronoamperometric response by 62%, which is attributed to a synergistic effect of large surface area and strong light absorption in the UV region by the presence of ZnO nanorod arrays.

This work investigates the growth and detachment of chemically formed micro-bubbles on micro-textured catalyst using a high-speed digital camera and simulation results. Three bubble growth stages were identified for single bubbles grown on circular type Pt catalyst. The first stage was inertia-controlled and the bubble diameter was directly proportional to time, and pertained when the bubble size was smaller than the Pt catalyst; in the second and third stages, gas was generated at a constant rate and the bubble diameter was varied as the cube root of time. However, in the third stage, the bubble growth rate is slightly lower than in the second stage, suggesting saturation. The calculation based on a mathematical model at constant gas generation rate is highly consistent with experimental results. The basic single bubble growth phenomenon was then adopted as a comparison to the bubble growth phenomena on textured catalyst structures. Experimental results revealed that a discontinuous mesh catalyst can effectively shorten the bubble detachment time when the substructures are thoroughly separated and the bubbles are larger than their initial size (*5 lm), while the concentric circular pattern does not. This study provides an insight into the growth and detachment phenomena of chemically formed micro-bubbles on catalyst of different textures, which is useful to the design of reactors for fuel cell systems.

In this paper, a facile two-step Galvanic replacement reaction (GRR) is proposed to prepare Pt-Ag tubular dendritic nano-forests (tDNFs) in ambient condition for enhancing methanol oxidation reaction (MOR) under solar illumination. In the first GRR, a homogeneous layer of silver dendritic nano-forests (DNFs) with 10 μm in thickness was grown on Si wafer in 5 min in silver nitride (AgNO3) and buffer oxide etchant (BOE) solution. In the second GRR, we utilized chloroplatinic acid (H2PtCl6) as the precursor for platinum (Pt) deposition to further transform the prepared Ag DNFs into Pt-Ag tDNFs. The catalytic performance and solar response of the Pt-Ag tDNFs toward methanol electro-oxidation are also studied by cyclic voltammetry (CV) and chronoamperometry (CA). The methanol oxidation current was boosted by 6.4% under solar illumination on the Pt-Ag tDNFs due to the induced localized surface plasmon resonance (LSPR) on the dendritic structure. Current results provide a cost-effective and facile approach to prepare solar-driven metallic electrodes potentially applicable to photo-electro-chemical fuel cells.

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