Porous yolk–shell microspheres as N–doped carbon matrix for motivating the oxygen reduction activity of oxygen evolution oriented materials

Abstract

It is highly challenging to explore high–performance bi-functional oxygen electrode catalysts for their practical application in next-generation energy storage and conversion devices. In this work, we synthesize hierarchical N–doped carbon microspheres with porous yolk–shell structure (NCYS) as a metal-free electrocatalyst toward efficient oxygen reduction through a template-free route. The enhanced oxygen reduction performances in both alkaline and acid media profit well from the porous yolk–shell structure as well as abundant nitrogen functional groups. Furthermore, such yolk–shell microspheres can be used as precursor materials to motivate the oxygen reduction activity of oxygen evolution oriented materials to obtain a desirable bi-functional electrocatalyst. To verify its practical utility, Zn–air battery tests are conducted and exhibit satisfactory performance, indicating that this constructed concept for preparation of bi-functional catalyst will afford a promising strategy for exploring novel metal–air battery electrocatalysts.

Breaking scaling relations in nitrogen reduction with asymmetrical heterobimetallic FeCo sites to boost ammonia synthesis

“…Fe single atom/FeCo dual atoms immobilized on N-doped hollow carbon nanospheres were prepared by optimized pyrolysis of a polypyrrole-metal coordination complex. 49,50 Inductively coupled plasma mass spectrometry characterizations were conducted and the elements Fe and Co were confirmed to occur in a 1 : 1 atomic ratio in the FeCoNC catalyst. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images show that both FeCoNC and FeNC catalysts exhibit an aperture spherical structure (Fig.…”

Nitrogen-doped hollow mesoporous carbon spheres for efficient oxygen reduction

“…Zinc-air batteries have become a cost-effective option for energy storage because of their outstanding energy density [4][5][6]. While the four-electron process offers higher power during energy conversion, its higher electrochemical energy barrier compared to the two-electron process leads to slower kinetics for the overall ORR [7]. Consequently, extensive research has been undertaken to explore potential catalysts that can enhance ORR activity.…”

Tailoring Carbon Materials Substrate to Modify the Electronic Structure of Platinum for Boosting Its Electrocatalytic Activity

“…Electrocatalysts toward oxygen reduction reaction (ORR) are highly important for various kinds of energy conversion devices, especially proton-exchange membrane fuel cells. [1][2][3][4][5][6][7][8][9][10] Although much progress has been made to develop the low-cost and efficient nonprecious metal catalysts for ORR, 11,12 platinum (Pt) based ORR catalysts are still the best choice in acidic medium due to their high kinetic activity, low overpotentials, as well as their good stability. 13,14 Except for the continuous efforts to exploit the efficient non-precious metal catalysts, the decrease of the supported Pt amount with high catalytic activity is also highly important to decrease the cost of catalysts.…”