MXenes: Multifunctional 2D materials for hydrogen evolution, energy storage, and carbon capture applications

Abstract

Ti₃C₂Tₓ MXene was synthesized by selective etching of Ti₃AlC₂ MAX phase using HF. Structural and surface properties were assessed via XRD, Raman, SEM, HRTEM, BET, and XPS, confirming Al removal, interlayer expansion, and functionalization with single bondF, –OH, and = O groups. The resulting MXene exhibited a specific surface area of 26.7 m2/g and pore size of 16.2 nm. A single batch was deployed in three applications: as an HER electrocatalyst in 1 M H₂SO₄, achieving −511 mV onset potential, 190 mA cm−2 at −760 mV, and a Tafel slope of 184 mV dec−1; as a supercapacitor electrode in 3 M KOH, with areal capacitance of 411.1 mF cm−2 and 86.9 % diffusion-controlled contribution; as a CO₂ adsorbent, achieving uptakes of 0.80 and 0.66 mmol g−1 at 0 °C and 25 °C, respectively. Adsorption data fitted best to the Radke–Prausnitz isotherm, indicating mixed physisorption–chemisorption. A techno-economic analysis yielded a production cost of ~2.83 €/g. These results demonstrate the multifunctionality and scalability of Ti₃C₂Tₓ MXene as a good material for hydrogen generation, energy storage, and carbon capture.