Internal\nElectric Field Engineering Induced by Co<sub>3</sub>O<sub>4</sub>/Bi<sub>2</sub>MoO<sub>6</sub> Nanotubes for\nTrifunctional Electrocatalytic and Photocatalytic Applications

Electrocatalytic water splitting is an intriguing technique\nfor\nclean energy production, and engineering heterojunctions with an internal\nelectric field (IEF) can significantly enhance the electrocatalytic\nperformance. In this paper, Co<sub>3</sub>O<sub>4</sub>/Bi<sub>2</sub>MoO<sub>6</sub> heterojunction nanotubes have been prepared via electrospinning\nand calcination and show stronger activity and stability than single-phase\nCo<sub>3</sub>O<sub>4</sub> and Bi<sub>2</sub>MoO<sub>6</sub> due\nto the so-called “1 + 1 > 2” synergistic effect induced\nby IEF. In particular, 1.00Co<sub>3</sub>O<sub>4</sub>/Bi<sub>2</sub>MoO<sub>6</sub> nanotube catalyst performed the overpotential toward\nhydrogen evolution reaction (HER) with 197 mV and oxygen evolution\nreaction (OER) with 332 mV at 10 mA<b>·</b>cm<sup>–2</sup>. Based on the enhancement of IEF verified by density functional\ntheory calculation, the extended photocatalytic degradation of tetracycline\n(TC) showed an efficiency of 68.5% within 200 min under visible light\nirradiation. This work provides a facile “one stone, three\nbirds’ strategy to construct nanotube heterojunctions and develops\nthe IEF mechanism from photocatalytic to electrocatalytic application.