A series of supported α-Ni(OH) 2 structures on etched halloysite nanotubes (eHAs) are synthesized via a one-pot facile co-precipitation method. By expediently controlling the variety of alkali source, etched halloysite nanotubes@α-Ni(OH) 2 (eHA@α-Ni(OH) 2 ) with different α-Ni(OH) 2 morphologies and Ni 2+ -ion contents can be achieved. The prepared eHA@α-Ni(OH) 2 is used to catalytically reduce 4-nitrophenol (4-NP). It shows that eHA@α-Ni(OH) 2 prepared with n-butylamine as an alkali source (eHA@α-Ni(OH) 2 -B) exhibits a higher k app of 1.458 × 10 −2 s −1 and K of 583.27 s −1 •g −1 . The catalytic reduction property is in accordance with the Ni 2+ -ion content of eHA@α-Ni(OH) 2 . Moreover, it also exhibits a good cycle stability due to the synergy of the support eHA and the supported Ni 2+ ions in α-Ni(OH) 2 , which can achieve a 99% 4-nitrophenol conversion after 11 cycles. The Ni 2+ -ion reduction experiment illustrates that the Ni 2+ ion is the activation site and the enhanced 4-NP reduction activity of eHA@α-Ni(OH) 2 -B is attributed to the higher Ni 2+ -ion content, which accelerates the electron transport from NaBH 4 to 4-NP to result in the catalytic reduction of 4-NP to 4-aminophenol (4-AP).

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