Preparation and characterization of nanosized nickel oxide
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Catalysis Letters Vol. 101, Nos. 3–4, June 2005 (Ó 2005) DOI: 10.1007/s10562-005-4899-x
Preparation and characterization of nanosized nickel oxide Chen-Bin Wang*, Guo-Yuan Gau, Shiue-Jiun Gau, Chih-Wei Tang, and Jia-Lin Bi Department of Applied Chemistry, Chung Cheng Institute of Technology, National Defense University, Tahsi, Taoyuan, 33509 Taiwan, Republic of China
Received 11 January 2005; accepted 27 January 2005
Nanosized nickel oxide was synthesized by a simple liquid-phase process to obtain the hydroxide precursor and then calcined to form the oxide. The precursor and the nickel oxide were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), thermal analysis (TG) and temperature-programmed reduction (TPR). The results indicated that the particle size of nickel oxide was controlled by the calcined temperature (TC). Mixed phases of nickel oxide and nickel hydroxide were present as the TC was lower than 300 °C. Non-stoichiometric nickel oxide (NiOx, x = 1.2) was formed between 250 °C and 400 °C and a pure nickel oxide was formed as the TC arrived 500 °C. The particle size of nickel oxide changed as the calcined temperature was controlled under 250 °C, 300 °C, 400 °C and 500 °C, the order was 5.6 nm, 6.5 nm, 11 nm and 17 nm, respectively. KEY WORDS: nickel oxide; nickel hydroxide; particle size.
1. Introduction Nanosized materials, such as metal oxides have attracted much attention recently because of their unusual chemical and physical properties which are different from those of bulk materials [1–3]. In particular, nanosized nickel oxides, NiO, are widely used in many technological applications because they exhibit particular catalytic [4,5], anomalous electronic [6,7] and magnetic [8, 9] properties. Another important application of NiO is in a battery system [10,11]. Non-stoichiometric nickel oxide is a good P-type semiconductor owing to its defect structure [12] and it is also a potential gas sensor for H2 [13]. These applications can be enhanced by decreasing the particle size, preferably to less than 10 nm, and are highly dependent on particle size; the precise control of the size and distribution in a nanometer regime is required. Techniques for the nano-scale particle preparation have been developed in the last years [14–16]: The chemical routes are widely used to produce a powder product owing to its relative simplicity and its low energy consumption. The present investigation is an attempt towards better controlling the preparation of non-stoichiometric nickel oxide (NiOx). For this purpose we choose a simple liquid-phase process to obtain the hydroxide precursor and then have it calcined to form the oxide. In this paper, we report the thermal behavior of Ni(OH)2 and NiOx particles and the characterization of nanosized NiOx particles (a controlled size in the 5–20 nm region). To accomplish this work object TG, * To whom correspondence should be addressed. E-mail: [email protected]
XRD, IR and TPR are performed to characterize the obtained nickel hydroxide and nickel oxide.
2. Ex
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