Simple and Fast Microwave-Assisted Synthesis Methods of Nanocrystalline TiO₂ and rGO Materials for Low-Cost Metal-Free DSSC Applications

Abstract

Nanocrystalline TiO 2 and reduced graphene oxide (rGO) materials have been synthesized by a simple and low-cost microwave-assisted hydrothermal method and applied in dye-sensitized solar cells (DSSCs) as photoactive and metal-free counter electrodes, respectively. Different TiO 2 nanocrystalline materials have been synthesized via the acid hydrolysis sol–gel method, followed by microwave hydrothermal treatment at 210 °C and 300 psi and at different microwave irradiation times (20, 30, 45, and 60 min) instead of the usual hydrothermal time of 12 h. The properties of the produced mesoporous nanocrystalline TiO 2 are investigated in terms of their morphology, crystal structure, optical properties, and surface area behavior using relevant characterization techniques. Maximum specific surface area values ( S BET ) of 97.77 and 100.7 m 2 g –1 are measured for TiO 2 , with the average crystallite sizes of 18.6 and 17.5 nm, at microwave irradiation times of 30 and 45 min, respectively. Different rGO samples have been prepared by the modified Hummers method, followed by microwave-assisted reduction at a temperature of 200 °C and pressure of 300 psi at different microwave irradiation times (3, 17, and 25 min). The physicochemical properties of the different rGO samples in terms of morphology, crystallization, and optical properties are characterized by TEM, XRD, and Raman spectroscopic analysis. The current density J sc of the fabricated DSSCs based on TiO 2 as the photoelectrode and rGO as the counter electrode compared with DSSCs based on Pt as the counter electrode is found to be 11.25 and 9.28 mA cm –2 , respectively. Although the overall power efficiency of the fabricated DSSCs based on rGO as the counter electrode is lower than that based on the Pt electrode, the former still exhibits promising prospects for replacing Pt with low-cost metal-free carbon-based DSSCs.

Leveraging novel microwave techniques for tailoring the microstructure of energy storage materials

“…For example, in microwave-assisted synthesis, non-thermal effects of microwave heating can directly transfer energy to the volume of the material, enabling rapid and uniform heating through the interaction of molecules with the electromagnetic field. Researchers optimized the synthesis of pure α-phase nickel hydroxide nanosheets using microwave heating, completing the process in just ten minutes at 150 °C without surfactants or additives, effectively controlling the phase and morphology of nickel hydroxide [63] . The pure α-phase nickel hydroxide nanosheets demonstrated excellent electrochemical performance in lithium-ion battery applications through microwave-assisted synthesis.…”

A Review on the Progress and Future of TiO2/Graphene Photocatalysts

“…Graphene-based TiO 2 composites have emerged as efficient photocatalysts [1,6,[182][183][184][185][186] for the next generation photocatalytic applications [1,105,[187][188][189][190][191][192]. The synergistic effect between components in ternary photocatalysts (comprising three components, where each photocatalyst component plays its potential role to maximize the photocatalytic activity) offers significant merits, such as multiple interfaces, improved separation and migration/transfer of charges, reduced recombination of photogenerated charge carriers, prevented agglomeration, high specific area and high stability [193].…”

Optimizing the Mechanoluminescent Properties of CaZnOS:Tb via Microwave-Assisted Synthesis: A Comparative Study with Conventional Thermal Methods

“…It is a fast and efficient method that can significantly reduce the synthesis time compared to traditional methods. The technique is based on the use of microwave energy to heat and excite the molecules of the material being synthesized, leading to a rapid and homogenous increase in temperature, and has many advantages over traditional synthesis methods, including: Furthermore, it is a versatile technique that can be used to synthesize a wide range of materials with improved properties and are readily applicable for industrial use [26,27].…”