Hollow-structured nanoreactors confine PdCu alloy nanoparticles to drive efficient catalytic hydrogenation

Abstract

Spatial confinement provides an effective strategy for constructing high-performance alloy nanoreactors by regulating local reaction microenvironments. Herein, a halloysite nanotube–confined PdCu alloy nanoreactor (PdCu3@HNTs-OH) is developed via an in situ growth strategy, enabling ultrasmall PdCu alloy nanoparticles (∼5 nm) to be selectively embedded within the nanotube lumen, forming a hollow, cell-biomimetic catalytic architecture. For comparison, PdCu3 alloy nanoparticles supported on the external surface of amino-functionalized halloysite nanotubes (PdCu3/HNTs-NH2) are prepared to elucidate the confinement effect. Benefiting from the void-confinement–induced microenvironment, the PdCu3@HNTs-OH nanoreactor exhibits markedly enhanced catalytic activity toward hydrogenation reactions, achieving complete reduction of 4-nitrophenol within 40 s with a turnover frequency of 2295 h−1. In addition, the nanoreactor demonstrates broad catalytic universality toward various organic dyes, including Congo Red, Methyl Orange, and Methylene Blue. Density functional theory calculations reveal that spatial confinement modulates the electronic structure of PdCu alloys, optimizes adsorption of key intermediates, and lowers reaction energy barriers, enabling an efficient six-step hydrogenation pathway. Moreover, the halloysite shell encapsulation strengthens metal–support interactions, significantly enhancing structural stability and recyclability. This work highlights spatial confinement within natural nanotubes as a powerful design principle for engineering efficient, stable, and versatile alloy nanoreactors.