Two-dimensional transition metal carbides/nitrides (MXenes) hold immense potential in cutting-edge fields such as energy storage, catalysis, electromagnetic shielding, and sensors, thanks to their metallic conductivity, abundant surface terminal groups, and excellent hydrophilicity.

However, mainstream MXene synthesis methods suffer from bottlenecks such as low efficiency, long processing times, and poor structural control. Furthermore, the generated nanosheets lack in-plane ion-transport channels and exhibit insufficient exposure of active sites, which limits their application in scenarios such as energy storage and high-efficiency desalination.

Although subsequent methods like oxidation or alkali treatment can introduce in-plane nanoholes into MXenes to improve ion accessibility, existing strategies generally adopt a two-step approach, "etching followed by hole-making", making it difficult to achieve an efficient, one-step conversion from the MAX phase to porous MXenes.

From a structural standpoint, this challenge stems from a kinetic mismatch between the oxidation of Ti sites and the removal of Al layers during etching, leading to over-oxidation of Ti atoms and uncontrollable pore formation.

Therefore, how to synergistically regulate the selective etching of the Al layer and the controllable oxidation of Ti sites within the same system to achieve in situ construction of in-plane pore structures while maintaining lattice integrity remains a key scientific issue for the efficient fabrication of high-performance porous MXenes.

To address these challenges, Professor Zhang Miao's team at the School of Chemistry, Xi'an Jiaotong University (XJTU), has proposed a radical-intensified selective etching (RISE) strategy. This strategy uses H₂O₂ to generate highly reactive hydroxyl radicals (·OH) in situ in a LiF/HCl system.

While accelerating the removal of Al atomic layers, the strategy regulates the radical content to achieve a controllable adjustment of the oxidation degree of Ti atoms. Unlike the traditional minimally intensive layer delamination (MILD) pathway that relies on protonic acids (H⁺), ·OH acts as an efficient electron acceptor dominating the oxidation process of Al and Ti.

An appropriate amount of ·OH yields high-quality monolayer MXenes with few defects and high electrical conductivity, whereas a slight excess of ·OH leads to the moderate oxidation of Ti atoms, forming uniform nanoholes on the MXene surface. This synthesis strategy requires only three hours to achieve the one-step synthesis of customized in-plane nanohole-structured MXenes with an etching efficiency of ∼99.9 percent.

Experimental results show that the porous MXene conductive thin film exhibits an outstanding desalination capacity of 32.71 mg g^-1 during capacitive deionization, outperforming pure MXene electrode materials.

This work is expected to revolutionize mainstream wet-chemical etching protocols for preparing monolayer MXenes and open an efficient, scalable synthesis pathway to tailor MXene structures for energy and environmental applications.

The research findings, titled One-Step Radical-Intensified Selective Etching (RISE) Strategy for High-Yield Synthesis of Monolayer MXene with Tailored Nanoholes, have been published in the internationally renowned journal Angewandte Chemie International Edition.