Lu Zhao,Yulong Qin,Chaoqun Chang,Xiqin He,Qi An,Yihe Zhang
The development of efficient and durable oxygen evolution reaction (OER) catalysts capable of operating at large current densities remains a critical challenge for renewable-energy technologies. Here, we report a Mo-doped FeCoNiCu high-entropy alloy (HEA) electrocatalyst that achieves enhanced OER activity and stability through high-valence Mo-induced lattice oxygen activation. The designed FeCoNiCuMo HEA nanoparticles exhibit low overpotentials of 340 mV at 100 mA cm–2, along with stability exceeding 650 h in alkaline media. Systematic studies reveal two key roles of Mo doping. It facilitates surface reconstruction by promoting lattice oxygen depletion and adsorbed oxygen generation. Meanwhile, it modulates the electronic structure of Ni sites to favor the formation of highly active β-NiOOH phases with shortened Ni–O bonds, a behavior distinctly different from Mo-free analogues. Furthermore, the FeCoNiCuMo HEA-based flexible zinc-air battery (FZAB) delivers a peak power density of 80 mW cm–2 with stable charge–discharge operation. This work offers a promising strategy for utilizing high-valence dopants to tailor the oxygen evolution pathway of HEAs for potential applications in energy conversion devices.
Linjing Qiao,Jianqiang Bi,Yao Yang,Guandong Liang,Shaoyin Wang,Hongyi Wang
Nowadays, the increasingly severe electromagnetic (EM) wave pollution requires high-performance EM wave absorbing materials. Multi-principal-element materials are acknowledged as promising for broadening the applications owing to their tunable chemistries and structures in many fields, including as EM wave absorbers. Herein, we prepared a high-entropy MXene , (Mo 0.25 Cr 0.25 Ti 0.25 V 0.25 ) 3 C 2 T x . Furthermore, multi-principal-element (Mo 0.25 Cr 0.25 Ti 0.25 V 0.25 ) 3 C 2 T x /FeCoNi and (Mo 0.25 Cr 0.25 Ti 0.25 V 0.25 ) 3 C 2 T x /FeCoNiCu composites were synthesized via an in-situ hydrothermal process by combining high-entropy MXene with medium-entropy magnetic alloys . In contrast with the relatively narrow effective absorption bandwidth (EAB) of (Mo 0.25 Cr 0.25 Ti 0.25 V 0.25 ) 3 C 2 T x MXene (2.56 GHz), (Mo 0.25 Cr 0.25 Ti 0.25 V 0.25 ) 3 C 2 T x /FeCoNi composite with 50 wt% MXene can attain an optimum EAB of 4.88 GHz with the matching thickness of only 1.73 mm. As for (Mo 0.25 Cr 0.25 Ti 0.25 V 0.25 ) 3 C 2 T x /FeCoNiCu composites, both the absorption efficiency and absorption bandwidth are significantly enhanced. The combination of multi-principal-component strategy and composite construction endows the composites with synergistic dielectric and magnetic losses, optimized impedance matching as well as enhanced attenuation ability, thus improving EM wave absorption performances. In addition, radar cross section (RCS) simulation confirms that the prepared composites have broad application prospects as radar stealth materials.
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