With high theoretical capacity (926 mAh g −1 ) and safer voltage platform, Iron phosphide (FeP) as an anode material for lithium ion batteries has attracted a lot of attention. However, FeP also suffers serious capacity fading and unsatisfied rate capability, which are triggered by inferior intrinsic conductivity and large volume expansion. Herein, oriented by density functional theory (DFT) calculations, MOF-derived porous FeP nanorods modified by abundant P vacancies (denoted as V-FeP) were ingeniously designed via a simplified approach to alleviate the above obstacles. As a result, the V-FeP nanorods electrode delivered extraordinary specific capacity (1228.3 mAh g −1 at 0.1 A g −1 after 120 cycles) and long-cyclic performance (590.7 mAh g −1 at 2.0 A g −1 after 1000 cycles). Transmission electron microscopy, X-ray absorption fine structure, electron paramagnetic resonance and so on were used to character the V-FeP nanorods. The results indicated the supernormal electrochemical performances of V-FeP nanorods were originated from abundant P vacancies and good distribution of FeP nanoparticles in conductive carbon network, which enhanced electrical conductivity, provided more active sites, shortened the diffusion distances of Li ions and relieved the volume variations. The strategy demonstrates a further direction to effectively improve the lithium storage performance of transition metal phosphides.
Designing high-performance and earth-abundant bifunctional catalysts for electrocatalytic water splitting remains a great challenge. Herein, a novel electrode composed of Cr-doped Co 2 P with P vacancies nanowire arrays (denoted as CrCo 2 P(V p ) NWs) grown on nickel foam was fabricated via a hydrothermal and successive calcination method. The Cr doping and vacancy engineering synergistically enable the exposure of more active sites, optimize electronic structure, and accelerate the charge transport capability, thus enhancing the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performances. As a result, the obtained Cr 0.4 Co 2 P(V p ) NWs catalyst exhibits superior catalytic activities in 1.0 M KOH solution with low overpotentials of 37 mV at −10 mA cm −2 for HER and 253 mV at 20 mA cm −2 for OER, respectively. Furthermore, using Cr 0.4 Co 2 P(V p ) NWs as a dual-function catalyst only requires 1.54 V voltage at 10 mA cm −2 for overall water splitting. Notably, the Cr 0.4 Co 2 P(V p ) NWs catalyst displays satisfactory stability with only a small attenuation of 3.2% after 50 h in a constant current testing. This study highlights the synergistic effect between doping and anion-vacancies in the enhancement of electrocatalytic activities and provides a feasible strategy to design effective, earth-abundant, and stable bifunctional electrocatalysts for water splitting.
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