Recent progress in the application of qPlus-type non-contact atomic force microscopy in surface structure analysis

Precise surface structural characterization cornerstones surface science research. Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) are widely employed for surface structure analyses. However, STM cannot always confirm atomic positions through local density of states in structural characterization, and can only be used on conductive samples. In contrast, the qPlus-type non-contact AFM (qPlus-AFM) overcomes these drawbacks while achieving atomic resolution, making it an increasingly prominent and widely applied technique in surface structure determination. This review systematically introduces the working principle and imaging characteristics of qPlus-AFM, with a particular focus on its applications and advantages on surface structural characterization in surface organic molecules, hydrogen-bond-driven self-assemblies, and model catalysts. Finally, taking the striped structure of iron carbide as an example, we highlight the crucial role of qPlus-AFM in unveiling complex surface structures in heterogeneous catalysis.