Robust template-activator cooperated pyrolysis enabling hierarchically porous honeycombed defective carbon as highly-efficient metal-free bifunctional electrocatalyst for Zn-air batteries

Defect and Doping Co-Engineered Non-Metal Nanocarbon ORR Electrocatalyst

“…From the above, all kinds of pores have their own unique advantages for electrocatalysis. Hence, developing hierarchically porous nanostructure in carbon-based electrocatalyst is highly desirable [ 71 – 73 , 111 , 114 – 116 ]. By employing natural porous banana peel as precursor along with KOH activation, we developed a defective N-doped graphene-like nanosheets ORR catalyst that owns extremely high specific surface area (1756 m 2 g −1 ) and 3D interconnected hierarchical porous structure [ 110 ], as confirmed by the SEM and TEM images and N 2 adsorption–desorption isotherm and pore size distribution results (Fig.…”

Nanocarbon-based metal-free and non-precious metal bifunctional electrocatalysts for oxygen reduction and oxygen evolution reactions

“…It was only confirmed that the synergistic effect of N and S atoms was the key to the improvement of catalytic performance. Although DFT calculations indicated that structure of ''graphitic N"-S-graphene related with better bifunctional catalytic activity [22,111], more questions of the active sites in N, S co-doping/functionalization catalysts have not been answered like (1) which atoms correspond with ORR activity or OER activity; (2) if N atoms bond with S atoms; (3) how is the interactor between N and S.Besides N, P and N, S codoping/functionalization nanocarbon materials which are most studied, another heteroatoms co-doping/functionalization nanocarbon materials were also used as the metal-free bifunctional catalysts for ORR/OER such as N, B co-doping/ functionalization, N, O co-doping/functionalization, N, F codoping/ functionalization, P, S co-doping/functionalization, and N, P, S tri-doping/ functionalization nanocarbon was even prepared as the bifunctional catalyst [113][114][115][116][117][118][119][120]. The studies have demonstrated these minority metal-free bifunctional catalysts can also catalyze the ORR/OER and have a reasonable stability.Consequently, it is obvious that heteroatoms both mono-and multidoping/functionalization of nanocarbon materials can reduce metal-free electrocatalysts active for the ORR/OER in the alkaline solutions.…”

Transition Metal and Nitrogen Co‐Doped Carbon‐based Electrocatalysts for the Oxygen Reduction Reaction: From Active Site Insights to the Rational Design of Precursors and Structures

“…The template-mediated method using hard and soft templates is a common and effective strategy for synthesizing hierarchically porous materials for ORR. Various hard templates, such as silica (e. g., SiO 2 ), [120][121] metal oxides/hydroxides/carbonates/sulfides (e. g., MgO, CaO, Fe 3 O 4 , Mg(OH) 2 , Ca(OH) 2 , CaCO 3 , ZnS), [88,122] metal chlorides (e. g., NaCl, KCl, ZnCl 2 ), [123] and polystyrene sphere (PS), [124] etc., have been developed to tailor the porous structure of the ORR catalysts. Shui's group used mesoporous SiO 2 as a template, and then preheated and etched to achieve a concave-shaped atomic FeÀ NÀ C catalyst with increased mesopores and external surface area.…”