Hierarchical porous one-dimensional N-doped C framework comprising ultrafine Mo2C catalysts for stable Na/K–Se batteries: Experimental and theoretical investigations

Herein, we designed one-dimensional (1D) highly porous and conductive N-doped carbonaceous framework (P–N–C) with ultrafine molybdenum carbide (Mo 2 C) catalysts and applied it as host for Se infiltration (Se@P–N–C@Mo 2 C). The final product demonstrates reversible insertion/de-insertion of Na/K-ion with high rate capability and stable cycling performance. • Porous and conductive N-doped carbonaceous framework (P–N–C) is prepared. • Well-integrated with ultrafine molybdenum carbide (Mo 2 C) catalysts. • Se infiltrated (Se@P–N–C@Mo 2 C) product utilized for sodium/potassium batteries. • Electrophilic coupling interaction between M o δ + and S e x 2 - . This study explores the integration of a highly porous and conductive N-doped carbonaceous framework (P–N–C) with ultrafine molybdenum carbide (Mo 2 C) catalysts and utilized it as an outstanding cathode host for Se infiltration (Se@P–N–C@Mo 2 C). The one-dimensional (1D) porous structure is obtained by typical electrospinning, followed by carbonization. The complete thermal decomposition of the elongated polystyrene phase generates 1D continuous macroporous tunnel-like channels, and subsequent potassium hydroxide (KOH) activation induces micropore formation. The macroporous channels facilitate easy electrolyte percolation, ensuring smooth and rapid electron/ion diffusion by decreasing the diffusion length and accommodating undesirable volume perturbations. The KOH-induced micropores enable the efficient infiltration of high Se amounts. Additionally, N-doping in the carbon species enhances the electronic conductivity of the nanostructure. The ultrafine Mo 2 C catalysts facilitate the efficient trapping and electrocatalytic conversion of Na/K–polyselenide species via an electrophilic coupling interaction between M o δ + and S e x 2 - in Mo 2 C and Na 2 Se x or K 2 Se x species, respectively, thereby enhancing active-material utilization. Consequently, the cell comprising the Se@P–N–C@Mo 2 C cathode exhibits high-rate capability (up to 10.0C) and long-term cycling stability at 0.5C and 1.0C (400 cycles each), when tested for Na-ion storage. Similarly, a high and stable discharge capacity, 235 mA h g −1 (87 % retention, 220 cycles), is observed at a C-rate of 1.0C in K-ion storage. As an anode in full-cell configuration, the Se@P–N–C@Mo 2 C electrode achieves reversible Na/K-ions insertion/de-insertion, highlighting its suitability for commercial applications.