Amorphous-crystalline heterostructure for simulated practical water splitting at high-current–density

Abstract

Heterostructure (WO 2 -Ni 17 W 3 )/NiFe(OH) x /NF with amorphous-crystalline interface as bifunctional catalyst for efficient water splitting at high current density. • Amorphous-crystalline interface modifies the electronic structure of catalyst for accelerating water electrolysis. • The formation of NiFe(OH) x stabilizes the catalyst for efficient H 2 and O 2 evolution at high current density. • Ultra-high stability with 120 h at 1000 mA cm −2 under simulated industrial condition (6.0 M KOH solution at 60 ℃). The catalyst for practical water electrolysis needs to maintain long-term stability and work effectively withstanding high-intensity gas evolution, which is extremely challenging. Heterostructure with an amorphous-crystalline interface has been reported recently to availably enhance the catalytic performance of materials at high output. Herein, a wet chemical etching method realizes the hierarchical amorphous/crystalline heterostructure [(WO 2 -Ni 17 W 3 )/NiFe(OH) x ]. It induces modulated electronic structure and abundant active sites with chemical stability, resulting in extraordinary catalytic activity for hydrogen evolution reaction ( η 10 = 31 mV, η 1000 = 258 mV), oxygen evolution reaction ( η 50 = 240 mV, η 1,000 = 336 mV), and overall water splitting (1.54/1.84 V at 50/1,000 mA cm −2 ). Besides, it can maintain at 1,000 mA cm −2 stably for 120 h under simulated industrial condition (6.0 M KOH solution at 60 ℃) as a bifunctional catalyst. The coupled active phases and the in-situ formed heterojunction ensure an excellent performance at high current density. This strategy could be promoted to fabricate catalysts for practical water electrolysis.