Abstract
Ti(3)C(2)T (x) (T (x) denotes terminal group), resulting from two-dimensional (2D) Mxenes, has attracted significant attention due to energy shortage and catalysis. Herein, we present reproducible 2D Ti(3)C(2)T (x) obtained from commercial bulk Ti(3)AlC(2) using a cost-effective and environment-friendly approach. Both etching and exfoliation processes were investigated with the rational selection of etchant, reaction time and exfoliation solution. The hydrofluoric acid (HF) etchant plays a key role in the production of 2D Ti(3)C(2)T (x) and therefore the recycling of HF is addressed for reproducible 2D MXenes. Hazardous HF waste was also neutralized via CaF(2) precipitation according to the regulations for HF sewage. Equally important, dimethyl sulfoxide (DMSO) was employed to promote the exfoliation of multilayer Ti(3)C(2)T (x) MXenes into Ti(3)C(2)T (x) nanosheets in an aqueous solution, which can couple with terminal groups and protect the exfoliated single-layers from recombination, facilitating interface passivation toward perovskite solar devices. The resulting perovskite solar cell exhibited striking improvements to achieve champion efficiency, with a PCE of 19.11%, which accounts for ∼9% enhancement as compared to pristine devices.