JNCASR scientists find new stable form for gold, expands its industrial applications

Scientists have introduced new catalytic properties in gold by altering the most stable FCC lattice, converting it into a new avatar that can trigger gold-based catalysis for industry.

The unique property of `Au’ is mainly dictated by its atomic arrangement in the crystal structure, technically called face-cantered cubic (FCC) lattice.

Tuning of crystal structures and shapes of micro-sized noble metals or micro-crystallites have revealed fascinating catalytic, optical, electrical, and magnetic properties that enable developments of environmentally friendly and durable nano-technological applications.

Gold has been a fascinating metal for use in jewellery and well as industrial applications because of its high resistance against conventional oxidizing environments. 

The team guided by Prof GU Kulkarni from JNCASR has succeeded in stabilising `Au’ in mixed lattices consisting of lower symmetry lattices in the form of micro-crystallites, induced by geometrical constraints. In contrast to conventional bulk FCC gold, these micro-crystallites are more efficient in their catalytic activity. Besides, the crystallites behave nobler than the conventional FCC `Au’ in mercury and aqua regia. Thus, these `Au’ crystallites behave quite differently from our day to day used ones, and the credit goes to the underlying unconventional lattices.

This research published in the journal ACS Nano’ was supported by the Department of Science & Technology, DST provided within the framework of the India@Desy collaboration and Nano Mission and the technical support from the EU-Horizon 2020 research and innovation programme of Nanoscience Foundries and Fine Analysis (NFFA).

The JNCASR team included Prof MK Sanyal from SINP, Kolkata who used scanning X-ray diffraction microscopy (SXDM) technique with nano-beam at Deutsches Elektronen-Synchrotron(DESY), PETRA III, Germany, which revealed location of the spatial distribution of the different lattices in the crystallite volume without using any slicing techniques.

The study disclosed many surprises. The central part of the crystallite is rich in lower symmetry lattices while being capped by the FCC rich tips, which explains their unique behavior in aqua regia. Besides, co-presence of compression and expansion to the extent of approximately 5 per cent (compared with conventional FCC `Au’) in the micrometer-sized crystallite helps the crystallites remain ambient stable for years. Such study of the spatial distribution of the different phases can allow exploration of new properties in a much better way.