Research Projects

MXenes are a class of 2D transition metal carbides, nitrides, and carbonitrides with the general formula Mn+1XnTx , where M is an early transition metal (e.g., Ti, V, Nb), X is carbon and/or nitrogen, and Tx denotes surface functional groups such as –OH, –O, and –F. First discovered by Naguib et al. in 2011 through selective etching of MAX phases, MXenes have since attracted extensive research attention due to their tunable electronic structure, high electrical conductivity (~10⁶ S/m), large specific surface area, and excellent mechanical strength. These properties make MXenes promising candidates for thermoelectric (TE) composites. However, challenges remain in utilizing conventional MXenes for TE applications: (i) high intrinsic thermal conductivity of pristine MXene sheets (~10 W/m-K for Ti₃C₂) limits phonon scattering efficiency (ii) spontaneous oxidation in air or moisture can degrade performance and (iii) restacking of nanosheets can reduce interfacial effectiveness and anisotropy. To overcome this, entropy-engineered MXenes, containing multiple transition metal elements in the M-site, have emerged as a novel class with suppressed phonon transport due to enhanced lattice disorder, defect density, and interfacial mismatch. High-entropy MXenes, by design, introduce additional phonon scattering centers, effectively reducing the lattice thermal conductivity and potentially boosting the thermoelectric figure of merit (ZT). In this project, we aim to synthesize a next-generation thermoelectric composite by reinforcing CoSb₃-based skutterudites with high-entropy MXene nanosheets. Synthesis will be done inside the glovebox to avoid oxidation. Unlike conventional MXenes, high-entropy MXenes offer synergistic benefits: atomic-scale disorder suppresses phonon transport via enhanced mass and strain field fluctuations, while their metallic conductivity supports high carrier mobility, both essential for optimizing the thermoelectric figure of merit (zT). The layered morphology of MXene further provides a platform for tailoring grain boundary structure and enabling interfacial phonon scattering, potentially decoupling thermal and electrical transport. We are also intent to adopt a cost- effective synthesis route. Also, to avoid oxidation during the composite fabrication process, all the sample will be processed inside a glovebox. Our research is strategically positioned to deliver a mid-temperature thermoelectric generator with n-type legs of In-filled CoSb₃ and p-type legs of Ce/Br-filled CoSb₃ skutterudite. Change in the coefficient of thermal expansion (CTE) of both n-type and p-type materials will be calculated after fabricating their composites with MXene. As a joining material, we are planning to use ‘Ag’ paste along with thin silver wires to connect legs electrically in series. After preparing a device using skutterudite legs with zT above 1, we’ll perform the power output measurement in the 50˚C to 550˚C temperature range.