Abstract

Electrochemical water splitting to prepare hydrogen, including hydrogen evolution reaction (HER), is considered as one of the green and practical approaches for the wide application of new energy sources. During this process, efficient catalyst is essential to hydrogen production efficiency. Wherein, nickel–cobalt complex sulfides (CoS@NiS) with few layers and large contact area is an emerging cost-effective catalyst for hydrogen production. However, traditional hydrothermal synthesis process implemented in the stirred tank reactor, because of its low heat and mass transfer efficiency, resulted in long reaction time and high energy consumption, limiting the scale-up production and synthesis efficiency. In this work, an efficient continuous synthesis platform based on microreactor was designed to prepare high-performance and few-layer CoS@NiS nanosheets with porous structure of petaloid clusters and wrinkled defects edge. By optimizing experimental conditions, the prepared CoS@NiS nanosheets exhibited excellent electrocatalysis performance for HER with low overpotential of 157 mV at 10 mA·cm−2, small Tafel slope of 75.9 mV·dec-1 and long-term catalytic stability. It was worth noting that the HER activity of CoS@NiS nanosheets obtained in continuous flow platform within 20 min was higher than that in the traditional stirred tank reactor over 12 h (182 mV at 10 mA·cm−2 and 93.3 mV·dec-1), significantly improving the synthesis efficiency. The continuous flow synthesis platform provides an efficient and convenient solution for the scale-up production of high-performance electrocatalytic nanomaterials.