Easy hydrothermal synthesis of external mesoporous γ-Al2O3 nanorods as excellent supports for Au nanoparticles in CO oxidation

•An easy synthesis of NH4Al(OH)2CO3 nanorods without templates is developed.•Decomposition of NH4Al(OH)2CO3 could create pores on the external surface of γ-Al2O3.•External mesopores can act as “holders” to stabilize Au nanoparticles efficiently.•The prepared catalyst exhibits excellent performance for CO oxidation (T100% = 18 °C).

External mesoporous γ-Al2O3 nanorods with an aspect ratio of 2–4 has been hydrothermally synthesized using Al(NO3)3·9H2O as precursor and (NH4)2CO3 as precipitant without any templates and followed by a calcination step. The obtained samples were characterized by thermogravimetric analysis (TG), X-ray powder diffraction (XRD), nitrogen sorption, Fourier transform infrared spectrometry (FT-IR), and scanning transmission electron microscopy (STEM). It can be confirmed that the morphology of nanorods is formed in the low-temperature hydrothermal process of 100 °C. Through the thermal decomposition of intermediate product NH4Al(OH)2CO3, the prepared γ-Al2O3 possesses abundant external mesopores, which can act as “holders” to stabilize or anchor gold nanoparticles efficiently. Using CO oxidation as an probe reaction, the results demonstrated that Au catalyst exhibited excellent catalytic performance with the complete CO conversion at 18 °C (T50% = −11.2 °C) and reactive stability over 166 h under a space rate of 134,000 mL h−1 gcat−1.

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