Co_0.5Ni_0.5MoO₄ Double‐Shelled Hollow Spheres with Enhanced Electrochemical Performance for Supercapacitors and Lithium‐Ion Batteries

Abstract

Transition metal molybdates represent a promising family of electrode materials for supercapacitors and lithium‐ion batteries (LIBs). Herein, Co0.5Ni0.5MoO4 double‐shelled hollow spheres (DSHSs) are synthesized using a simple and scalable spray‐drying method followed by calcination in air. Benefited from the unique hollow structure as well as the coexistence of Co and Ni, the as‐synthesized Co0.5Ni0.5MoO4 DSHSs exhibit an improved pseudocapacitive property with a specific capacitance of 731 F g−1 at 0.5 A g−1 and a high capacitance retention of 91% (10 A g−1) after 5000 cycles. In addition, the obtained Co0.5Ni0.5MoO4 DSHSs also manifest a high specific capacity (900 mAh g−1 at 0.2 A g−1 after 50 cycles) and an excellent cyclability (756 mAh g−1 at 1 A g−1 after 1000 cycles) for lithium storage. This rational design on both component and structure provides an effective strategy to achieve high‐performance supercapacitors and LIBs.

Genuine Active Species Generated from Fe3N Nanotube by Synergistic CoNi Doping for Boosted Oxygen Evolution Catalysis

“…Additionally, because Fe, Co, and Ni are adjacent to each other in the periodic table with similar atomic radius and mass, they are apt to form a solid solution phase or substitute with each other, and Co(Ni)Fe 2 O 4 is formed on the internal wall of NT with a floating content of Fe and doped Co(Ni). [26,27] Notably, compared with Fe y N, the (110), (002), (111), and (112) peaks of Fe 3 N in CoNi-Fe 3 N shift to lower angles (right of Figure 2g and Figure S6, Supporting Information), indicating the lattice expansion after Co and Ni doping, which enlarges the atomic Fe−N/Fe bonds and weakens atomic interactions. [28] To further analyze chemical composition and the valence states of Fe 3 N based NTs, X-ray photoelectron spectroscopy (XPS) was carried out.…”