Sliding catalysis for on-off switching of the hydrogen evolution reaction on two-dimensional van der Waals bilayers

The emerging sliding ferroelectricity engineered by stacking nonpolar two-dimensional materials to form van der Waals (vdW) multilayers has led to the important field of slidetronics, which has attracted broad interest from those working in the fields of condensed matter physics, chemistry, and materials science. Here, we explore the promising territory of sliding ferroelectricity, termed ``sliding catalysis,'' through extensive first-principles calculations on various two-dimensional bilayer materials for on-off switching of a prototypical chemical process, the hydrogen evolution reaction. It is revealed that, by overcoming a negligible sliding-energy barrier, the two surfaces of the vdW bilayers exhibit reversible Janus catalysis, with one surface presenting enhanced performance and the other degenerate. Moreover, it is found that the larger the dipole moment of the bilayer is, the better the catalytic performance becomes, and importantly, the more effective the on-off switching functionality. The present concept of sliding catalysis is expected to direct the development of high-efficiency, particularly high-selectivity, two-dimensional catalytic platforms.