(n1,...,np)-quasi-m-isometric commuting tuple of operators on a Hilbert space
ANNALS OF FUNCTIONAL ANALYSIS
Authors: Cho, Muneo; Beiba, El Moctar Ould; Mahmoud, Sid Ahmed Ould Ahmed
Abstract
Our aim in this paper is to consider a generalization of the concept ofn-quasi-m-isometric operators of a single operator done in Mahmoud Sid Ahmed et al. (Results Math 73:511-531, 2018) and Mechri and Mahmoud Sid Ahmed (Oper Matrices 14(1): 145-157, 2020) to the multi-dimensional operators. We discuss the most interesting results concerning these classes of tuples of operators by extending some results obtained in several recent papers for a single operator.
Influence of the phosphorus source on iron phosphide nanoparticle synthesis for hydrogen evolution reaction catalysis
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
Authors: Park, Yoonsu; Kang, Hyeri; Hong, Yun-kun; Cho, Geonhee; Choi, Miri; Cho, Jiung; Ha, Don-Hyung
Abstract
Iron phosphide (FeP) is in the spotlight as a hydrogen evolution reaction (HER) catalyst due to its cost efficiency, good catalytic activity, and stability within a wide pH range. However, there is still a need to synthesize FeP nanoparticles (NPs) with systematic analysis to improve their catalytic activity. Herein, we report FeP NPs synthesized with various phosphorus sources (TOP, trioctylphosphine; TPP, triphenylphosphite; TEAP, tris(diethylamino)phosphine; and TBP, tri-n-butylphosphine) via phosphorization reaction. We clearly demonstrate that the HER activity of the catalyst based on the FeP phase is dependent on the choice of phosphorus source used in the colloidal NP synthesis. Among the samples, FeP NPs synthesized with TPP achieved the highest HER activity with an overpotential of 76 mV at 10 mA cm(-2) in 0.5 M H2SO4. Our results reveal a critical aspect of colloidal synthesis to achieve enhanced catalytic activity in the synthesis of transition metal phosphide NPs. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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