Overview
The common thread in this work is the relation between how a material is made, the microstructure that results, and the properties that follow. In thermoelectric alloys, phase morphology and interfaces can be used to tune thermal and electrical transport; in electrochemical materials, the same relation governs catalytic activity and charge storage. The programme also applies these methods to waste-derived and locally sourced materials, where processing is constrained by cost and availability.
Current direction
I am developing an interest in data-driven approaches to microstructure and property relationships in thermoelectric alloys, and I welcome collaboration with groups working in this area.
Research themes and representative papers
Thermoelectric alloys and microstructure design
Solidification, eutectic morphology and interfacial effects in Bi–Sb–Te and related systems, and their consequences for transport and mechanical behaviour.
- Olu, Ravishankar and Chattopadhyay, J. Mater. Sci. (2016) Microstructure evolution and thermoelectric properties of Te-poor and Te-rich (Bi,Sb)2Te3 prepared via solidification
- Legese and Olu, J. Indian Inst. Sci. (2022) A review of lamellar eutectic morphologies for enhancing thermoelectric and mechanical performance
- Kumar, Muse, Olu et al., Acta Mater. (2023) Fe addition in PbTe–Ni diffusion-bonded thermoelectric contact interfaces
- Jigi et al., J. Alloys Compd. (2025) Directionally solidified Bi2Te3–AgBiTe2 eutectic and the energy filtering effect
Half-Heusler and high-entropy thermoelectrics
- Kumar et al., J. Alloys Compd. (2022) Zr-based quaternary half-Heusler alloy systems: phase evolution, crystal structures and electronic properties
- Adamo et al., Energy Technol. (2024) Integrated first-principles and experimental investigation of Zr/Ti half-Heusler-type high-entropy alloys
- Haile et al., Adv. Eng. Mater. (2025) Direct ink writing of a double-half-Heusler thermoelectric high-entropy alloy
Two-dimensional tellurides
- Siddique et al., Mater. Today (2021) Emerging two-dimensional tellurides
- Siddique et al., ACS Appl. Nano Mater. (2021) Scalable synthesis of atomically thin gallium telluride nanosheets for supercapacitor applications
Electrocatalysis, energy storage and sensors
- Regasa et al., ACS Omega (2020) Molecularly imprinted conducting-polymer film electrochemical sensor for melamine in infant formula
- Woldetinsay et al., Mater. Res. Express (2021) Effect of support material on the electrocatalytic activity of palladium nanoparticles toward hydrogen evolution
- Emiru et al., New J. Chem. (2026) Hybrid phosphazene-based COP/PANI/CNT composites for high-performance supercapacitors
Waste valorisation and environmental materials
- Desalegn, Bekele and Olu, Sci. Rep. (2023) Optimization of Cd(II) removal using a natural hydroxyapatite/bentonite composite
- Assefa et al., Desalin. Water Treat. (2024) Advances in adsorption technologies for hexavalent chromium removal
- Kochito et al., Sci. World J. (2024) MnOx–coffee husk and khat leftover biochar nanocomposites for methylene blue removal
Thermophysical properties of superalloys
- Singh, Olu, Pandey and Chattopadhyay, J. Alloys Compd. (2021) Thermophysical and magnetic properties of Co–Ni–Mo–Al–Ta class of tungsten-free Co-based superalloys
Research in brief
Thermoelectric materials and microstructure design
This strand examines how composition, solidification route and interfaces jointly shape the thermoelectric behaviour of bulk alloys. It began with doctoral work on Bi–Sb–Te alloys at the Indian Institute of Science (Olu, Ravishankar and Chattopadhyay 2016) and has continued through studies of eutectic anisotropy (Mukherjee et al. 2021), lamellar eutectic morphologies (Legese and Olu 2022) and Zr-based half-Heusler high-entropy alloys (Adamo et al. 2024, 2025). Together these suggest that the scale and orientation of coexisting phases can matter as much as composition.
Electrocatalysis, sensors and energy storage
This strand concerns conducting-polymer and carbon-based composites for electrochemical applications. Early work used molecularly imprinted polyaniline-based films as sensors for melamine in infant formula (Regasa et al. 2020). Later studies examined palladium and nickel-based catalysts on reduced graphene oxide for hydrogen and oxygen evolution (Woldetinsay et al. 2020, 2021), nickel phosphide electrodes for alkaline urea oxidation (Lera et al. 2021, 2022, 2023), and phosphazene-based covalent organic polymer composites as supercapacitor electrodes (Emiru et al. 2025, 2026). These papers suggest that the interface between the polymer, the carbon support and the active phase is the shared design variable, although the evidence comes from separate systems and not from a single comparative study.
Two-dimensional tellurides
This strand concerns atomically thin telluride materials and their functional behaviour. It includes a review of emerging two-dimensional tellurides (Siddique et al. 2021), the scalable synthesis of gallium telluride nanosheets for supercapacitor electrodes (Siddique et al. 2021), and studies of cobalt telluride as a piezo-triboelectric generator, as an energy-harvesting layer and as a magnetically assisted photocatalyst (Negedu et al. 2022). An earlier computational study predicted a two-dimensional piezomagnet in silicene and transition-metal systems (Dzade et al. 2010). Most of this work was collaborative.
Superalloys and structural alloys
This strand addresses the thermophysical and mechanical behaviour of metallic alloys for demanding service. It includes a study of the thermophysical and magnetic properties of tungsten-free Co–Ni–Mo–Al–Ta superalloys (Singh et al. 2021), work on the processing and tensile behaviour of aluminium alloys (Han et al. 2017; Perugu et al. 2022), and a patent on nickel–aluminium–zirconium alloys (Tiwary et al. 2017). More recent studies extend the interest to three-dimensionally printed composites (Bukate et al. 2025). The published record in superalloys itself is limited to a small number of papers.
Ore beneficiation, waste recovery and sustainable materials
This strand uses locally available minerals and wastes as feedstock for functional materials. It includes magnetite nanoparticles from Ethiopian iron ore (Sebehanie et al. 2020), iron-oxide pigments from mill-scale steel slag (Eticha et al. 2022), and biochar nanocomposites from coffee husk and khat residues for removing methylene blue and hexavalent chromium from water (Kochito et al. 2024). Related studies examine hydroxyapatite–bentonite adsorbents for cadmium (Desalegn et al. 2023), self-healing coal fly ash bricks (Kedir et al. 2023) and keratin films from poultry waste (Assefa et al. 2025). Much of this work was done with doctoral and MSc students at Jimma University.
Processing and synthesis methods
Rapid solidification
Rapid cooling to refine microstructure and to improve mechanical and thermoelectric properties.
Ultrasonication
Ultrasonic-assisted synthesis of two-dimensional nanomaterials for functional applications.
Hydrothermal synthesis
Low-temperature crystallisation for producing nanoparticles and thin films.
Solvothermal synthesis
Controlled synthesis of inorganic and hybrid materials in solvent-based systems.