Construction of MOF-derived hollow sugar gourd-like Ni-Co-S@NiMoO4•xH2O nanocage arrays for efficient solar-powered overall water splitting

Abstract

In situ growth of nanoarrays on conductive substrates is an efficient strategy for designing electrocatalysts. However, preparing array with excellent catalytic activities for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) remains a challenge. Here, we construct a novel hollow sugar gourd-like Ni-Co-S@NiMoO4·xH2O/NF nanocage array through MOF derivation strategy for stable solar-driven overall water splitting. Due to the hollow core–shell structure and multi-component advantages, the Ni-Co-S@NiMoO4·xH2O/NF presents high density of active sites and fast charge transfer rate. Therefore, Ni-Co-S@NiMoO4·xH2O/NF exhibits attractive electrocatalytic activity in alkaline electrolytes for HER (90 mV@10 mA cm−2) and OER (208 mV@10 mA cm−2, 245 mV@100 mA cm−2). The corresponding two-electrode electrolytic cell demonstrates small cell voltage (1.515 V @ 10 mA cm−2) and shows durability over 50 h at 10 mA cm−2, exhibiting excellent overall water splitting performance. It is worth noting that the solar-assisted electrolysis cell reaches a high solar-to-hydrogen (STH) conversion rate of 19.4 %. The construction of this unique hollow structure gives a fascinating method for improving the HER and OER performance of transition metal sulfide electrocatalysts.