Hierarchically wood-derived integrated electrode with tunable superhydrophilic/superaerophobic surface for efficient urea electrolysis

Conferring surfaces with superhydrophilic/superaerophobic characteristics is desirable for synthesizing efficient gas reaction catalysts. However, complicated procedures, high costs, and poor interfaces hinder commercialization. Here, an integrated electrode with tunable wettability derived from a hierarchically porous wood scaffold was well designed for urea oxidation reaction (UOR). Interestingly, the outer surface of the wood lumen was optimized to the preferred wettability via stoichiometry to promote electrolyte permeation and gas escape. This catalyst exhibits outstanding activity and durability for UOR in alkaline media, requiring only a potential of 1.36 V (vs. RHE) to deliver 10 mA cm−2 and maintain its activity without significant decay for 60 h. These experiments and theoretical calculations demonstrate that the nickel (oxy)hydroxide layer formed through surface reconstruction of nickel nanoparticles improves the active sites and intrinsic activity. Moreover, the superwetting properties of the electrode promote mass transfer by guaranteeing substantial contact with the electrolyte and accelerating the separation of gaseous products during electrocatalysis. These findings provide the understanding needed to manipulate the surface wettability through rational design and fabrication of efficient electrocatalysts for gas-evolving processes.