Enhanced tribological performance by interfacial nanoarchitectonics with ionic liquid-grafted N, P-doped Ti₃C₂T_x MXene nanosheets in oil-based lubrication

The formulation and improvement of high-efficiency lubricant additives on the basis of novel two-dimensional MXene materials have drawn increasing attention in recent years. Herein, we report the synthesis of N, P doped Ti₃C₂T_x MXene using ammonium hypophosphite as the N/P source, followed by surface modification with catechol-containing ionic liquid to obtain ionic liquid-functionalized MXene. Tribological tests reveal that ILs@N, P‑MXene markedly improve the tribological properties of 500SN with 0.75 wt% addition. Compared with the lubricant 500SN, the mean COF is reduced to 0.107, the wear volume decreases by 65.8%, and their load-carrying ability is improved to 650 N from 150 N. XPS analysis indicates that ILs@N, P-MXene undergoes tribochemical reactions with the steel substrates during sliding, forming a continuous and stable protective tribofilm comprising carbonitrides, iron oxides, titanium oxides and iron phosphates. This in-situ formed tribofilm successfully inhibits direct asperity contact between the mating surfaces, thereby endowing the lubricant system with good load-carrying capacity and improved tribological performance.