Decoration of Pt–Ni Alloy on Molten Salt Etched Halloysite Nanotubes for Enhanced Catalytic Reduction of 4-Nitrophenol

Efficient and low-cost nanocatalysts are extremely desirable for the catalytic reduction of 4-nitrophenol (4-NP). A smaller nanocatalyst particle size and stronger support effect can significantly enhance the catalytic performance. Naturally occurring halloysite nanotubes (HNTs) are promising alternative supports for fine metal nanoparticles, but the smooth surface and single type of functional groups on HNTs are usually unfavorable for the anchoring of metal ions. Herein, we modified HNTs using a mild and controllable molten salt etching method to create a rough surface (rHNTs), followed by loading Pt–Ni alloys to prepare Pt–Ni/rHNTs for the catalytic reduction of 4-NP. The results demonstrate that ultrafine Pt–Ni alloy nanoparticles with a diameter of 1.60 nm are uniformly dispersed on the rough surface of rHNTs. The particle size and catalytic performance can be tuned by adjusting the loading amount of Pt–Ni. The optimized Pt–Ni/rHNT (1 wt %) nanocatalyst reveals the smallest Pt–Ni particle size and the highest catalytic rate of 0.1953 min−1, which exceeds many Pt–Ni-based catalysts in previous reports. This work offers an ingenious idea for the mild surface modification of HNTs and a brilliant perspective for the rational design of inexpensive 4-NP reduction nanocatalysts.