Superhydrophilic and heterostructured NiCu/polyaniline nanocomposites as highly efficient electrocatalyst and photothermal conversion layer integrated thermoelectric device for overall water splitting

Abstract

The large-scale production of green hydrogen from water electrolysis has recently gained extensive attention. However, the high overpotential leads to the excessive costs of electricity consumption. Herein, a novel research scheme was proposed to design photothermal electrocatalyst with photothermal effect and highly efficient hydrogen evolution reaction (HER) performance, which can be integrated with thermoelectric (TE) device to effectively lower the cell voltage in the overall water splitting. Experimental and DFT calculations results demonstrated that NiCu/PANI/NF catalyst displayed superior HER performance (28 mV@10 mA cm−2, 89 mV@50 mA cm−2), exceptional durability (110 h@10, 50 mA cm−2), as well as good infrared photoresponsivity (93.4 ℃@200 mW cm−2 @10 min). It can be mainly attributed to the synergy of polyaniline and the introduction of Cu, which can effectively modulate the d-band center of Ni active site, and attenuate H adsorption energy, then promote H2 generation. Additionally, superhydrophilicity of NiCu/PANI/NF can facilitate mass transfer and accelerate H2 evolution. Notably, in a self-designed electrolyzer-TE integrated device, the cell voltage was significantly lowered for the overall water splitting (0.29 V @50 mA cm−2). This work presented an efficient photothermal electrocatalyst and provided novel insights for investigations into water electrolysis with cost-effective hydrogen production in the future.