In situ transformation of Co-MOF nanorods into Co3S4/Ni3S2 nanotube arrays for electrochemical biomass upgrading

Electrocatalytic oxidation has emerged as an efficient method for upgrading biomass to value-added products. Herein, hollow Co3S4/Ni3S2 nanotube arrays were synthesized in one pot on nickel foam (NF) under solvothermal conditions (120 C-degrees, ethanol, 3 h), using thioacetamide (TAA) additive and Co metal-organic framework (Co-MOF) nanorod arrays as the template. The in situ transformation of nanorods into nanotubes occurred via ion exchange and synchronous etching processes in which Co-MOF nanorods provided Co2+, NF provided Ni2+ and TAA provided S2- that enabled the reassembly of constituents into Co3S4/Ni3S2 nanotube arrays. The nanotube arrays applied as electrodes for electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) exhibited a wide potential application range from 1.35 to 1.7 V vs. RHE and afforded nearly 100% 2,5-furandicarboxylic acid yields and faradaic efficiencies (FE). The as-prepared Co3S4/Ni(3)S(2)electrodes were applied to furfural, furfuryl alcohol and benzyl alcohol to form the corresponding acid products at yields and FE of up to 99.2% and 98.3%, respectively. The hollow structure of Co3S4/Ni3S2 nanotube arrays improves electron transport, expands the specific surface area, and increases substrate access to active catalytic sites, and the simple fabrication method greatly expands the scope for preparing non-noble metal-based nanotube arrays for electrocatalytic applications.

Automated summary

In this study, hollow Co3S4/Ni3S2 nanotube arrays were synthesized as electrodes for electrocatalytic oxidation of biomass, achieving excellent results.