Tubular nanoreactor with unique void-confinement effect has captured great attention for catalytic applications but is challenging in controllable fabrication and realizing a synergistically enhanced performance. Herein, a template polymerization-guided synthetic strategy is presented to confine hollow Prussian blue analog boxes inside conducting polypyrrole nanotubes (H-CoFe PBA@PPy NTs) as efficient peroxymonosulfate activator toward catalytic oxidation of toxic organic contaminants. This delicately designed H-CoFe PBA@PPy NTs display a superior kinetic rate constant compared with the pristine CoFe PBA cubes (7.9 fold) and H-CoFe PBA boxes (22.6 fold). Experimental evidence reveals that the generation of multiple reactive oxygen species in the nanotubes plays a vital role for the significantly enhanced catalytic efficiency for dye degradation. The superior catalytic performance is attributed to the intrinsic bimetallic CoFe PBA to provide abundant active sites, distinct nanotubular structure to concentrate the reactant molecules within a confined space, and excellent electron/mass transport property. This work presents new horizons for the design of high-efficiency and stable catalysts with space confinement effects to promote future advanced water treatment technology.

The design of void-confined tubular nanostructures has aroused significant interest for catalytic applications because of their distinct microenvironment to modulate the reaction kinetics. Herein, we propose a facile wrapping-pyrolysis strategy to confine Fe 0 nanoparticles (Fe NPs) inside N-doped carbon nanotubes (Fe@NC NTs) derived from Fe 2 O 3 @polypyrrole (PPy) core-sheath nanofibers (NFs). The resultant Fe@NC NTs can act as efficient enzyme mimics and exhibit a significantly higher peroxidase (POD)-like catalytic activity than unconfined Fe NPs and bare NC NTs. Kinetic experiments demonstrate that the optimized void structure benefits the affinity with the POD substrates and achieves excellent catalytic efficiency. The mechanism study reveals that the generation of • OH from H 2 O 2 endows Fe@NC NTs with excellent POD-like performance. Furthermore, we develop a total antioxidant capacity (TAC) sensing platform on account of this efficient POD-like system, expanding their applications in the field of food safety and human healthcare.

The design of a hierarchical heterostructure as a cost-effective and high-efficiency catalyst to realize electronic and interfacial engineering for the oxygen evolution reaction (OER) is a meaningful option in energy storage and conversion. In this work, amorphous NiFeS nanosheets supported on carbon nanofibers embedded with cobalt nanoparticles (Co-C/NiFeS nanofibers) catalysts are fabricated via the electrospinning-carbonization-electrodeposition strategy. The optimized catalyst possesses a superior OER activity with a low overpotential of 233 mV at 10 mA cm −2 and a Tafel slope of 53.1 mV dec −1 in 1 mol L −1 KOH solution, together with a favorable hydrogen evolution reaction activity. Moreover, an alkaline Pt/C||Co-C/NiFeS electrolyzer constructed with Co-C/NiFeS nanofibers as the anode and commercial Pt/C as the cathode achieves a low cell voltage of 1.48 V at 10 mA cm −2 , which is superior to those of the benchmark Pt/C||RuO 2 cell and many other reported electrolyzers. As a bifunctional electrocatalyst, the Co-C/NiFeS||Co-C/NiFeS electrolyzer can be assembled, exhibiting outstanding long-term stability of 70 h, which significantly outperforms that of the Pt/C||RuO 2 electrolyzer. The remarkable OER performance of the catalyst benefits from the distinct hierarchical heterostructure with Co-C nanofibers core and amorphous NiFeS nanosheets sheath and the generated highly conductive fibrous carbon substrate, endowing it with a large number of exposed active sites, great electrical conductivity and impregnable structural stability. Thus, this work demonstrates a facile and efficient approach to fabricate non-noble metal-based catalysts with superior electrocatalytic performance for practical energy conversion and storage.

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