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The metastable α-phase GaO is an emerging material for developing solar-blind photodetectors and power electronic devices toward civil and military applications. Despite its superior physical properties, the high quality epitaxy of metastable phase α-GaO remains challenging. To this end, single crystalline α-GaO epilayers are achieved on nonpolar ZnO (112̅0) substrates for the first time and a high performance Au/α-GaO/ZnO isotype heterostructure-based Schottky barrier avalanche diode is demonstrated. The device exhibits self-powered functions with a dark current lower than 1 pA, a UV/visible rejection ratio of 10 and a detectivity of 9.66 × 10 cm Hz W. Dual responsivity bands with cutoff wavelengths at 255 and 375 nm are observed with their peak responsivities of 0.50 and 0.071 A W at -5 V, respectively. High photoconductive gain at low bias is governed by a barrier lowing effect at the Au/GaO and GaO/ZnO heterointerfaces. The device also allows avalanche multiplication processes initiated by pure electron and hole injections under different illumination conditions. High avalanche gains over 10 and a low ionization coefficient ratio of electrons and holes are yielded, leading to a total gain over 10 and a high responsivity of 1.10 × 10 A W. Such avalanche heterostructures with ultrahigh gains and bias-tunable UV detecting functionality hold promise for developing high performance solar-blind photodetectors.

2000255 (1 of 9) Pd-based nanosheet materials have emerged as efficient catalysts for monobasic and polyhydric alcohol oxidation reactions. However, most reported synthetic methods of Pd-based nanosheets (NSs) are nonuniversal and surfactant-involved, leading to residue-covered surfaces with drastically damaged electrocatalytic properties. Herein, a universal, surfactant-free, simple one-pot route is developed for the precise synthesis of a kind of novel self-standing Pd-M (M = Ag, Pb, Au, Ga, Cu, Pt, etc.) NSs with tremella-like superstructures are assembled using ultrathin two-dimensional (2D) NSs. Benefiting from the universal surfactant-free methods, the obtained Pd-M NSs exhibit clean surfaces and stable three-dimensional (3D) self-standing structures that overcome the difficulty of normal close packing and overlapping 2D NSs. The Pd-M (M = Ag, Pb, and Au) NSs with tremella-like structures all show excellent ethanol oxidation reaction (EOR) and ethylene glycol oxidation reaction (EGOR) properties. In particular, with the optimal superstructure, better electronic effect, and promoted toxicity tolerance, the EOR/EGOR mass activities of Pd 7 Ag NSs, Pd 7 Pb NSs, and Pd 7 Au NSs are 8.2/7.3, 7.2/5.7, and 5.3/4.4 times higher than that of commercial Pd/C catalysts. This advanced 3D construction also endows Pd-M NSs with more favorable stability than Pd/C. This study may be extended to Pd-M (M = other metals) NSs and open up more opportunities for broad catalytic applications.

In this article, a clean method for the synthesis of PtPd/reduced graphene oxide (RGO) catalysts with different Pt/Pd ratios is reported in which no additional components such as external energy (e.g., high temperature or high pressure), surfactants, or stabilizing agents are required. The obtained catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), induced coupled plasma atomic emission spectroscopy (ICP-AES), and electrochemical measurements. The HRTEM measurements showed that all of the metallic nanoparticles (NPs) exhibited well-defined crystalline structures. The composition of these Pt-Pd/RGO catalysts can be easily controlled by adjusting the molar ratio of the Pt and Pd precursors. Both cyclic voltammetry (CV) and chronoamperometry (CA) results demonstrate that bimetallic PtPd catalysts have superior catalytic activity for the ethanol oxidation reaction compared to the monometallic Pt or Pd catalyst, with the best performance found with the PtPd (1:3)/RGO catalyst. The present study may open a new approach for the synthesis of PtPd alloy catalysts, which is expected to have promising applications in fuel cells.