Supplementary cementitious materials are considered a viable and affordable way to reduce CO₂ emissions from the cement industry’s perspective since they can partially or nearly entirely replace ordinary Portland cement (OPC). This study compared the impact of adding spent coffee grounds (SCGs), fly ash (FA), and volcanic ash (VA) to two types of cement: OPC and calcium sulfoaluminate cement (CSA). Cement samples were characterized using compressive strength measurements (up to 210 days of curing), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), attenuated total reflection infrared spectroscopy, and hydration temperature measurements. In all the studied systems, the presence of SCGs reduced compressive strength and delayed the hydration process. CSA composite cement containing 3.5% SCGs, 30% FA, and 30% VA showed compressive strength values of 20.4 MPa and 20.3 MPa, respectively, meeting the minimum requirement for non-structural applications. Additionally, the results indicate a formation of cementitious gel, calcium silicate hydrate (C-S-H) in the OPC-based composite cements, and calcium alumino-silicate hydrate (C-A-S-H) as well as ettringite in the CSA-based composite cements.

Supercapacitors, at the forefront of energy storage, bridge the gap between traditional capacitors and batteries, renowned for high power densities, rapid charge/discharge rates, and extended cycle life. MXenes, two-dimensional transition metal carbides, nitrides, and carbonitrides, have emerged as promising supercapacitor electrode materials due to remarkable electrical conductivity and tunable surface properties. This chapter explores MXene-based supercapacitors, detailing synthesis methods, electrochemical performance, and potential applications. MXene-based supercapacitor performance, covering specific capacitance, energy density, power density, and cycling stability, is discussed. The chapter also addresses challenges in MXene-based supercapacitor development, including scalability, cost-effectiveness, and long-term stability, applications in portable electronics, wearables, and electric transportation. Providing a comprehensive overview, this chapter inspires further exploration and utilization of MXene-based supercapacitors for next-gen energy storage solutions.