Nanoconfined Topochemical Conversion from MXene to Ultrathin Non-Layered TiN Nanomesh toward Superior Electrocatalysts for Lithium-Sulfur Batteries

2D non-layered materials (2DNLMs) featuring massive undercoordinated surface atoms and obvious lattice distortion have shown great promise in catalytic/electrocatalytic applications, but their controllable synthesis remains challenging. Here, a new type of ultrathin carbon-wrapped titanium nitride nanomesh (TiN NM@C) is prepared using a rationally designed nano-confinement topochemical conversion strategy. The ultrathin 2D geometry with well-distributed pores offers TiN NM@C plentiful exposed active sites and rapid charge transfer, leading to outstanding electrocatalytic performance tackling the sluggish sulfur redox kinetics in lithium-sulfur batteries (LSBs). LSBs employing TiN NM@C electrocatalyst deliver excellent rate capabilities (e.g., 304 mAh g(-1) at 10 C), greatly outperforming that of using TiN nanoparticles embedded in carbon nanosheets (TiN NPs@C) as a benchmark. More impressively, a free-standing electrode for LSBs with a high sulfur loading of 7.3 mg cm(-2) is demonstrated, showing a high peak areal capacity of 5.6 mAh cm(-2) at a high current density of 6.1 mA cm(-2). This work provides a new avenue for the facile and controllable fabrication of 2DNLMs with impressive electrocatalysis for LSBs as well as other energy conversion and storage technologies.

Automated summary

A new type of ultrathin carbon-wrapped titanium nitride nanomesh was successfully prepared using a designed nano-confinement topochemical conversion strategy, showing outstanding electrocatalytic performance for lithium-sulfur batteries. The material offers plentiful exposed active sites and rapid charge transfer, resulting in excellent rate capabilities and high peak areal capacity. This work provides a new avenue for the facile and controllable fabrication of 2D non-layered materials with impressive electrocatalysis for various energy technologies.