Dr. Hong Ngee Lim is a senior lecturer at the Department of Chemistry, Faculty of Science, Universiti Putra Malaysia. Her current research interests are fabrication of graphene-based materials and their applications in energy storage, solar conversion and sensing platform. She is the principal researcher of international grants such as Newton Fund Institutional Links 2015, COMSTECH-TWAS Research Grants 2013 and Loreal Malaysia For Women in Science Fellowships 2011. She is the recipient of the Merdeka Award Grant for International Attachment 2014. She is also the principal researcher of various national grants funded by the Ministry of Science, Technology and Innovation, and Ministry of Higher Education. She has published about 100 ISI-cited journal articles. She is currently the Managing Editor of the International Journal of the Institute of Materials Malaysia.

 

Research Highlight

Photo-supercapacitor: A Marriage between Supercapacitor and Solar Cell

Malaysia is blessed with an abundance of solar energy all year long, making it one of the most feasible, sustainable and renewable energies available in the world. Solar conversion devices convert solar energy to usable electrical energy. The electrical energy captured from the solar energy is used to power up various electrical items from nanoelectronics to vehicles. The consumption of electrical energy from solar conversion may not be exhaustive and there may be an access of electrical energy. Hence, supercapacitors are realistic energy storage devices to store and deliver the excess electrical energy.

The motivation of a photo-supercapacitor is to convert, store and deliver electrical energy in a single device. Materials science and engineering plays a vital role in ensuring the maximum conversion, storage and delivery of electrical energy in a photo-supercapacitor. Graphene is a two-dimensional honeycomb sp2-hybridised carbon atoms that is able to maximise the properties of photo-supercapacitor owing to its high electron mobility, flexibility, mechanical durability and ease of functionalization. The derivatives of graphene encompass inorganic and organic graphenous materials. The inorganic grapheneous materials include functionalizing graphene with metals and metal oxides, whereas the organic grapheneous materials are functionalization of graphene with polymeric matrices.

The solar cells, for instance dye-sensitized solar cells, have been modified with grapheneous materials and are classified as platinum-free. The working electrode has been layered with graphene and metal oxide as a compact layer to prevent the back-transfer of electrons into the electrolyte. The counter electrode made from grapheneous materials is able to match the conventional platinum counter electrode, making the cells low-cost and longer-lasting. The grapheneous supercapacitor electrode materials are able to display outstanding capacitive values and excellent capacitive retention. The power density and energy density of the grapheneous supercapacitors are parallel with those of the supercapacitors available in the market.

Figure 1:
A Pt-free DSSC published in Journal of Power Sources 293 (2015) 712-720

Figure 2:
Supercapacitor published in Electrochimica Acta 157 (2015) 88-94

Figure 1:
Photo-supercapacitor published in Journal of Power Sources 296 (2015) 169-185