Heterointerface engineering of hollow CoP/CeO2 p-n heterojunction for efficient electrocatalytic oxygen evolution

Heterointerface engineering is a promising strategy to realize electronic redistribution and enhance oxygen evolution reaction (OER) activity. However, preparing and designing heterojunction with appropriate band structures and outstanding performance remains a challenge. Herein, a novel hollow CoP/CeO2 heterojunction (h-CoP/CeO2) is constructed by electrospinning and a selective phosphorization process. Hollow structure can create more active sites and promote the intimate contact between catalysts and electrolyte to facilitate the mass and charge transfer. Mott-Schottky plots demonstrate p-n heterojunction is formed between p-CoP and n-CeO2, which induces a strong intrinsic field and redistribution of charges. Attributed to its hollow structure and p-n heterojunction, the optimal h-CoP/CeO2 prepared with appropriate PVP content and [Co/Ce] ratio exhibits remarkable alkaline OER activity (overpotential = 198 mV at 10 mA cm(-2), Tafel slope = 83 mV dec(-1)). This result is better than or comparable to previous reports. Besides, h-CoP/CeO2 acing as a co-catalyst can improve the photoelectrochemical (PEC) performance of TiO2 nanorods, which not only increases the photocurrent density, but also reduces the onset potential (negatively shifted 58 mV for TiO2/CoP-CeO2). This study provided a new insight for constructing hollow heterojunction with uniform distribution of each component to enhance OER and PEC performance.