Designing hybrid transition metal compounds with optimized electronic structure and firmly dispersing them on a matrix to avoid aggregation and shedding is of great significance for achieving high electrocatalytic performances. Herein, an adsorption-complexation-calcination strategy based on channel confining effect is explored to obtain CoN-CoO_x hybrid nanoparticles uniformly dispersed in mesoporous carbon. The CoN-CoO_x/C composite exhibits excellent electrocatalytic behavior for oxygen reduction reaction (ORR). The half-wave potential and durability are comparable or superior to those of Pt/C. When applying as cathode catalyst for a primary zinc-air battery, the open-circuit voltage and peak power density reach up to 1.394 V and 109.8 mW·cm⁻², respectively. A high gravimetric energy density of 950.3 Wh·kg_Zn⁻¹ is delivered at 10 mA·cm⁻² with good rate capability and stability. Density functional theory (DFT) calculation demonstrates the favorable ORR intermediate adsorbability and metallic characteristics of CoN grains with oxide hybridization to optimize the electronic structure. This work provides a facile adjustable approach for obtaining highly dispersed nanoparticles with controllable hybrid composition on a substrate, which is important for future design and optimization of high-performance electrocatalysts.

Developing suitable electrode materials for electrochemical energy storage devices by biomorph assisted design has become a fascinating topic due to the fantastic properties derived from bio-architectures. Herein, zephyranthes-like Co₂NiSe₄ arrays grown on butterfly wings derived three-dimensional (3D) carbon framework (Z-Co₂NiSe₄/BWC) is fabricated via hydrothermal assembly and further conversion method. Benefiting from its unique structure and multi-components, the obtained Z-Co₂NiSe₄/BWC electrode for supercapacitor delivers an excellent specific capacitance of 2, 280 F·g⁻¹ at 1 A·g⁻¹. Impressively, the constructed asymmetric supercapacitor using Co₂NiSe₄/BWC as positive electrode and activated butterfly wings carbon as negative electrode acquires a high energy density of 42.9 Wh·kg⁻¹ at a power density of 800 W·kg⁻¹ with robust stability of 94.6% capacitance retention at 10 A·g⁻¹ after 5, 000 cycles. Moreover, the Z-Co₂NiSe₄/BWC as anode for sodium-ion batteries exhibits a high specific capacity of 568 mAh·g⁻¹ at 0.1 A·g⁻¹ and high cycling stability (maintaining 80.1% of the second cycle after 100 cycles). The outstanding electrochemical performances are ascribed to that the synergistic effect of bimetallic selenides and N-doped carbon improves electrochemical activities and conductivity. One-dimensional (1D) nanoneedles grown on 3D porous framework increase the exposure of redox-active sites, endow adequate transmission channels of electrons/ions, and guarantee stability of the electrode during charge/discharge processes. This study will shed light on the avenue towards extending such nanohybrids to excellent energy storage applications.

Sodium-ion batteries (SIBs) have been attracting considerable attention as a promising candidate for large-scale energy storage because of the abundance and low-cost of sodium resources. However, lack of appropriate anode materials impedes further applications. Herein, a novel self-template strategy is designed to synthesize uniform flowerlike N-doped hierarchical porous carbon networks (NHPCN) with high content of N (15.31 at.%) assembled by ultrathin nanosheets via a self-synthesized single precursor and subsequent thermal annealing. Relying on the synergetic coordination of benzimidazole and 2-methylimidazole with metal ions to produce a flowerlike network, a self-formed single precursor can be harvested. Due to the structural and compositional advantages, including the high N doping, the expanded interlayer spacing, the ultrathin two-dimensional nano-sized subunits, and the three-dimensional porous network structure, these unique NHPCN flowers deliver ultrahigh reversible capacities of 453.7 mAh·g^-1 at 0.1 A·g^-1 and 242.5 mAh·g^-1 at 1 A·g^-1 for 2,500 cycles with exceptional rate capability of 5 A·g^-1 with reversible capacities of 201.2 mAh·g^-1. The greatly improved sodium storage performance of NHPCN confirms the importance of reasonable engineering and synthesis of hierarchical carbon with unique structures.