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The catalytic production of aromatic azo compounds by aniline's oxidative coupling process is significant in organic synthesis. However, the catalysts used in this method generally exhibit low selectivity for the desired products and need costly preparation methods. In this study, for the first time, we proposed a species regulation strategy to synthesize the Rb-doped Cu/CeO2 nanorod catalyst, which showed high conversion (98%) and selectivity (95%) toward oxidative coupling of aniline to azoxybenzene using H2O2 as the oxidant. Aniline radical ion trapping experiments demonstrated that the oxidative coupling of aniline to azoxybenzene follows a nitrosobenzene intermediate mechanism. Characterization studies revealed that the addition of Rb not only enhances the interaction between Cu species and CeO2 but also increases oxygen vacancy content. DFT calculations indicate that the Cu–Ce and Rb–Ce interfaces are the main active sites, offering excellent catalytic performance. The reusability test for five cycles shows good stability of a Rb–Cu/CeO2 nanorod catalyst. The study provides a promising species regulation strategy for Rb-promoted nanocatalysts with ultrahigh selectivity, expanding their applicability in oxidative coupling and related reactions. [ABSTRACT FROM AUTHOR]

Aromatic azo compounds have proven to be a relevant class of building blocks in chemical synthesis. However, uncontrollable selectivity towards azo compounds and low reactant conversion in traditional synthetic methods seriously impede their applications. Herein, Rb‐doped Au/CeO2 nanocatalyst (Rb−Au/CeO2) was prepared and utilized as a highly efficient supported metal catalyst for the selective oxidation of anilines to azocompounds using hydrogen peroxide as an oxidant, which reached ultrahigh selectivity (92 %) towards azoxybenzene and complete aniline conversion (100 %). The addition of Rb+ accelerates the electron transformation of Au to produce Au+, which is ready for catalysis. This research presents a promising Rb‐doped strategy for achieving complete aniline conversion and high selectivity towards azoxybenzene, opening up new possibilities for the application of aromatic azo compounds in chemical synthesis. [ABSTRACT FROM AUTHOR]

Rational architectural design is the key to improve specific capacitance. Herein, we present a facile one-step hydrothermal process for the fabrication of a TiO2/RGO/MoO2 composite with an unprecedented 3D walnut-shaped hierarchical nanostructure, in which amorphous TiO2 is decorated on the RGO (reduced graphene oxide)/MoO2 surface via a Mo-involved in situ growth route on Mo net (TiO2/RGO/MoO2@Mo). This 3D structure coated with ultrafine arched nanorods is a great breakthrough in electrochemical performances of TiO2– or MoO2-based electrodes as it exhibits an extraordinary areal capacitance of 3927 mF cm−2 at 3 mA cm−2 (i.e. 1636 F g−1 at 1.25 A g−1) with only 3.5% capacitance loss after 5000 cycles. Such an excellent performance is benefitted from the following factors: (i) amorphous TiO2 sculptured MoO2 blocky particles supply more active-site accessibility and facilitate the accommodation of volume expansion. (ii) Arched MoO2 nanorods as well as the walnut-shaped spheres of the composite provide electron transfer paths. (iii) RGO is a soft scaffold, which relieves the volume expansion during the charge/discharge processes. [ABSTRACT FROM AUTHOR]

A roe-shaped ternary nanocomposite, Ni3(PO4)2/RGO/Co3(PO4)2 (NRC), was grown in situ on cobalt foam (CoF). The synthesis and loading of NRC on the CoF was completed through a one-step hydrothermal process by immersing the CoF in an aqueous solution of GO and Ni2+ in the presence of H2PO4−, in which the CoF served as the support, reductant and Co source. Three interfaces of Co3(PO4)2/CoF, RGO/Co3(PO4)2, and Ni3(PO4)2/RGO with strong interactions were constructed based on an in situ conversion reaction of Co to Co3(PO4)2, a redox reaction between GO and the CoF, and the electrostatic attraction force of Ni2+ and GO, respectively. The as-synthesized NRC@CoF had a hierarchically porous structure, and directly acted as a supercapacitor electrode and delivered excellent electrochemical performances: a specific capacitance of 10 237.5 mF cm−2 (1137.5 F g−1) at 5 mA cm−2 (0.56 A g−1) with a capacity retention of 117.8% after 14 000 cycles. Furthermore, NRC@CoF-based asymmetric supercapacitors (ASCs) exhibited a specific capacitance of 4845.9 mF cm−2 (115.4 F g−1) at 5 mA cm−2 (0.12 A g−1), and a high energy density of 44.82 W h kg−1 at a power density of 428.6 W kg−1, as well as good cyclic stability (91.9% after 18 000 cycles). [ABSTRACT FROM AUTHOR]