Renewable Energy Center

Solar Energy

In Search of Better Materials
K. Selva Raja

K. Selva Raja
Photo by Crista Hecht

Krishnan Selva Raja is a research assistant professor in chemical and materials engineering specializing in corrosion and electrochemistry. His research focuses on applying electrochemical tools and techniques to synthesizing and characterizing materials for energy conversion and storage. His current focus areas of research are development of quantum dot compound semiconductors and ferroelectric materials for solar energy conversion, hybrid materials for lithium ion batteries, development of novel non-consumable anode materials for reprocessing of spent nuclear oxide fuels, electrochemistry of reprocessing of spent nuclear fuels, and development of solid state welding techniques for joining exotic structural materials for advanced (Gen IV) nuclear reactors.  

Raja’s research on nanomaterials for energy application started with a grant from the National Science Foundation to synthesize and functionalize carbon nanotubes (CNT) using a templated process for various energy storage applications. Initially CNTs were grown on anodic alumina templates. In order to find a replacement for nanoporous alumina template, research on nanotubular titanium dioxide or TiO2 was started. Nanotubular TiO2 prepared by a simple anodization of Ti substrate has a wide variety of applications such as photo catalyst for degradation of organic pollutants; photo anode for hydrogen generation by splitting water using sunlight; substrate for bioimplants that shows enhanced osteo induction properties; and anode material for lithium ion batteries. It can also be used as a template for growing nanowires from various materials, like platinum nanowires and gold nanowires for fuel cells and biosensor applications.

In addition to nanotubular TiO2 , nanotubular iron oxide and nanoporous tungsten oxide materials have been developed following the simple anodization technique. The advantages of this anodization technique are its simplicity, scalability and low cost. Conventionally, nanomaterials are prepared by expensive vapor deposition techniques or by sol-gel method. Nanomaterials prepared by other wet-chemical methods require an additional step of electrode preparation that is integration of the nanomaterials to the current collector for most of the applications such as photovoltaic, fuel cell, battery, sensor and so on. The anodization route is a single-step process where self-ordered nanostructures are directionally in-situ grown on to a parent substrate that also acts as a current collector. Several patent applications have been filed based on these developments. The uniqueness of the processes developed at the University of Nevada, Reno is the ability to engineer the defect structure of the nanomaterials by modulating the electrochemical and thermal annealing parameters. 

Raja came to the University of Nevada, Reno in January 2001. Prior to that, he was working as a research associate in Tohoku University in Sendai, Japan where he worked on environmental degradation of pressure boundary components of nuclear light water reactors. Raja taught courses on corrosion to international students at Tohoku University. The required textbook for the corrosion course was Principles and Prevention of Corrosion, a text authored by Denny Jones, a professor at the University of Nevada, Reno. Impressed by Jones’ book, Raja wrote to Jones seeking an opportunity to work with him. Jones offered Raja a research position to work on corrosion-related research funded by Yucca Mountain project. Mano Misra took over the project and Raja continues to work with him on various energy and nuclear-related projects. With a research background in corrosion, Raja eventually shifted his focus to nanomaterials using his electrochemistry skills to prepare nanomaterials and developing a niche for synthesizing nanomaterials using electrochemical techniques.

Raja’s research group hopes to discover the ‘holy grail’ material for solar energy conversion with more than 45 percent efficiency and low cost (few cents/kWhr) so that utilization of renewable energy is economical for every household. The program is a blend of fundamental and applied research. The fundamental research is carried out using various analytical and mathematical tools in order to understand the big picture of grey areas that hinder the commercialization process. They focus on developing novel materials and methods for energy conversion and storage rather than inventing new theories. Raja works to develop nanomaterials of various types ranging from metals, oxides, and compound semiconductors using low cost, highly scalable electrochemical processes for applications such as solar energy conversion (photovoltaics), energy storage (batteries), bioimplants and sensors.