Dual heteroatom-doped carbons have attracted widespread research attention as catalysts in the field of energy storage and conversion due to their unique electronic structures and chemical tunability. In particular, boron and nitrogen co-doped carbon (B,N@C) has shown great potential for photo/electrocatalytic applications. However, more needs to be done for rational designing and regulating the structure of these materials to improve their catalytic performance. Herein, monodispersed hierarchical porous B,N@C nanocages were fabricated by pyrolyzing zeolite imidazole framework (ZIF) which was treated with ammonia borane or boric acid via an integrated double-solvent impregnation and nanocofined-etching method. The treated ZIF-8 provided an essential structural template to achieve B, N co-doped hierarchical structures with micro/meso/macro multimodal pore size distributions. The resultant B,N@C nanocages displayed high catalytic activities for electrochemical oxygen reduction reaction (ORR) in alkaline media, outperforming most carbon-based catalysts, particularly from the perspective of the half-wave potentials. Such high catalytic performance is due to the enhanced activity by the coexistence of B and N and the mass transfer promoted by the unique hierarchical porous structure.

Creating vacancy is often highly effective in enhancing the hydrogen evolution performance of transition metal-based catalysts. Vacancy-rich Ni nanosheets have been fabricated via topochemical formation of two-dimentional (2D) Ni₂B on graphene precursor followed by boron leaching. Anchored on graphene, a few atomic layered Ni₂B nanosheets are first obtained by reduction and annealing. Large number of atomic vacancies are then generated in the Ni₂B layer via leaching boron atoms. When used for hydrogen evolution reaction (HER), the vacancy-rich Ni/Ni(OH)₂ heterostructure nanosheets demonstrate remarkable performance with a low overpotential of 159 mV at a current density of 10 mA·cm⁻² in alkaline solution, a dramatic improvement over 262 mV of its precursor. This enhancement is associated with the formation of vacancies which introduce more active sites for HER along Ni/Ni(OH)₂ heterointerfaces. This work offers a facile and universal route to introduce vacancies and improve catalytic activity.