Chemical Technology January 2015

Minerals Processing & Metallurgy

UNIVERSITY OF PRETORIA In the pursuit of the ideals of excellence and diversity, the University of Pretoria wishes to invite applications for the following vacancies.

A significant number of papers have been published recently on nanoporous gold, but the precursor material is 30 wt% gold and 70 wt% silver. A similar dealloyed structure is obtained for the gold-silver system as for the AuAl 2 system. Potential applications for the nanoporous gold in- cludes: catalysis for oxygen-assisted coupling re- actions [36]; CO oxidation [29]; electro-catalysis/ fuel cells [15]; electrochemical immunoassays and sensors [37, 29, 46, 18]. Conclusions Precious metal intermetallic compounds are used in various applications as shown in this article. Although intermetallic compounds are inherently brittle, which could restrict their use in applica- tions, this limitation is overcome by using the compounds in powder form, coatings and inlays with bi-metallic castings. References References for this article are available from the editor at chemtech@crown.co.za. Acknowledgements 1. The Southern African Institute of Mining and Metallurgy, 2014. Advanced Metals Initiative, Department of Science and Technology. 2. This paper was originally presented at the Pre- cious Metals 2013 conference held in Cape Town, South Africa. 3. The Precious Metals Development Network (PMDN) is also thanked. z

PdIn Wang et al [44] developed a thermally stable, low-resistance PdIn ohmic contact to n -GaAs. A ~5nm layer of In 0,4 Ga 0,6 As covered the interface between the single phase intermetallic layer PdIn layer and the GaAs substrate. Specific contact resistivities and contact resistances of approximately 1×10 −6 Ωcm 2 and 0,14 Ωmm respectively, were obtained. Catalysis, sensors and capacitors Mesoporous, also known as nanoporous, gold and platinum can be prepared by deal- loying AuAl 2 and PtAl 2 in amanner analogous to that used in the preparation of Raney nickel catalysts [40]. The aluminium is then dissolved from the AuAl 2 precursor by means of NaOH to produce a highly porous gold structure (see Figure 7). Van der Lingen et al [41] produced heterogeneous catalysts by incorporating transition metal oxide(s) with the porous gold. Furthermore, promoter elements could also be melted with AuAl 2 to improve catalytic activity. These catalysts were tested for CO oxidation activity.

FACULTY OF ENGINEERING, BUILT ENVIRONMENT AND INFORMATION TECHNOLOGY DEPARTMENT OF CHEMICAL ENGINEERING 1 x permanent full-time 1 x contract appointment SENIOR LECTURER

The University of Pretoria wishes to appoint academic staff members in available positions to enhance the current research and teaching capacity in the Department of Chemical Engineering and to position the Department as an international leader. Expertise and experience are sought in the field of Environmental Engineering and in Water Utilisation Engineering. These positions will also be closely associated with multidisciplinary research related to renewable energy systems. The responsibilities will include: • Postgraduate and undergraduate teaching in the programme focus areas of the Department; • Assigned departmental duties (e.g. of an administrative nature); • Continuous research outputs in a productive manner within the research focus areas of the Department; • Expanding existing/initiating new research programmes, raising and managing additional funding from national and international funding agencies and industry to support the activities of the relevant focus group; • Publishing research articles in accredited journals; • Supervising postgraduate Master’s and Doctoral students. For details regarding the above position and information on how to apply, visit the University’s website at www.up.ac.za and follow the link: Careers@UP. APPLICATION DETAILS

Figure 7: HRSEM image of dealloyed AuAl 2 surface [41]. Pattrick et al [22] studied mesoporous gold catalysts prepared via dealloying of AuAl 2 for the selective catalytic reduction of NO x by propene under lean-burn condi- tions for potential autocatalyst applications. It was found that relatively low additions of platinum group metals (1 at.%) caused shifts to lower temperature regions of activity, with the largest shift obtained for rhodiummost likely due to a strong synergis- tic interaction between rhodium and gold. Cortie and Van der Lingen [3] investi- gated the potential of mesoporous gold for ultra-capacitors, and preliminary work revealed a perceived capacitance of about 15 to 28 mF as demonstrated for a sample containing 2 g of gold when connected as a cathode. No storage of energy was observed when the gold was connected as the anode.

CLOSING DATE: 13 FEBRUARY 2015

The University of Pretoria is committed to equality, employment equity and diversity. In accordance with the Employment Equity Plan of the University and its Employment Equity goals and targets, preference may be given, but is not limited to candidates from under represented designated groups. The University of Pretoria reserves the right not to make an appointment to the post as advertised.

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Chemical Technology • January 2015

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