Development of single-site catalysts supported by ultrathin two-dimensional (2D) porous matrix with ultrahigh surface area is highly desired but also challenging. Here we report a cocoon silk chemistry strategy to synthesize isolated metal single-site catalysts embedded in ultrathin 2D porous N-doped carbon nanosheets (M-ISA/CNS, M = Fe, Co, Ni). X-ray absorption fine structure analysis and spherical aberration correction electron microscopy demonstrate an atomic dispersion of metal atoms on N-doped carbon matrix. In particular, the Co-ISA/CNS exhibit ultrahigh specific surface area (2105 m2 g−1) and high activity for C–H bond activation in the direct catalytic oxidation of benzene to phenol with hydrogen peroxide at room temperature, while the Co species in the form of phthalocyanine and metal nanoparticle show a negligible activity. Density functional theory calculations discover that the generated O = Co = O center intermediates on the single Co sites are responsible for the high activity of benzene oxidation to phenol.

Porous CoNC catalysts with ultrahigh surface area are highly required for catalytic reactions. Here, a scale-up method to synthesize gram-quantities of isolated Co single-site catalysts anchored on N-doped porous carbon nanobelt (Co-ISA/CNB) by pyrolysis of biomass-derived chitosan is reported. The usage of ZnCl 2 and CoCl 2 salts as effective activation-graphitization agents can introduce a porous belt-like nanostructure with ultrahigh specific surface area (2513 m 2 g −1 ) and high graphitization degree. Spherical aberration correction electron microscopy and X-ray absorption fine structure analysis reveal that Co species are present as isolated single sites and stabilized by nitrogen in CoN 4 structure. All these characters make Co-ISA/CNB an efficient catalyst for selective oxidation of aromatic alkanes at room temperature. For oxidation of ethylbenzene, the Co-ISA/CNB catalysts yield a conversion up to 98% with 99% selectivity, while Co nanoparticles are inert. Density functional theory calculations reveal that the generated CoO centers on isolated Co single sites are responsible for the excellent catalytic efficiency.

Development of noble-metal single atomic site catalysts with high metal loading is highly required for many important chemical reactions but proves to be very challenging. Herein, we report a Na 2 CO 3 salt-assisted one-pot pyrolysis strategy from EDTA−Pt complex to N-doped graphene with isolated Pt single atomic sites (Pt-ISA/NG) with Pt loading up to 5.3 wt %. The X-ray absorption fine structure analysis and spherical aberration-correction electron microscopy demonstrate an atomic dispersion of single Pt species on graphene support and stabilized by nitrogen in Pt−N 4 structure. The Pt-ISA/NG catalyst exhibits high catalytic activity and reusability for anti-Markovnikov hydrosilylation of various terminal alkenes with industrially relevant tertiary silanes under mild conditions. In hydrosilylation of 1-octene, the Pt-ISA/NG catalyst delivers an overall turnover frequency of 180 h −1 , which is a 4-fold enhancement compared with commercial Pt/C.

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Monodispersed mesoporous hollow spheres of polymer-silica and carbon-silica nanocomposites with an "interpenetration twin" nanostructure have been successfully synthesized by a co-sol-emulsion-gel method. The obtained mesoporous hollow carbon spheres (MHCSs) exhibited an open interconnected mesoporous shell that is endowed with high specific surface area (SBET, 2106-2225 m(2) g(-1)) and large pore volume (1.95-2.53 cm(3) g(-1)). Interestingly, the diameter of the uniform MHCSs could be precisely tuned on demand, as an effective electrode material in supercapacitors, MHCSs with a diameter of 90 nm deliver the shortest time constant (τ0 = 0.75 s), which is highly beneficial for rate capacitance (180 F g(-1) at 100 A g(-1), a full charge-discharge within 0.9 s) and cyclic retainability (3% loss after 20,000 cycles). The newly developed synthesis route leads to unique interconnected mesoporous hollow carbonaceous spheres with open-framework structures, providing a new material platform in energy storage.