BiCoAl layered triple hydroxides with porous structure as bifunctional catalyst for efficient urea electrolysis

The production of hydrogen through urea electrolysis exhibits many advantages such as low consumption, cost-effectiveness, high efficiency, and environmental friendliness. Here, a layered triple hydroxide (BiCoAl-LTH) was grown in situ on nickel foam (NF) to prepare a self-supported electrode. The BiCoAl-LTH/NF electrode exhibits a unique two-dimensional array structure. Since Al is easily etched in a strong alkaline solution, a large number of oxygen vacancies are generated, which is conducive to improving the conductivity of BiCoAl-LTH/NF catalyst and thereby enhancing its urea oxygen reaction (UOR) activity. The BiCoAl-LTH/NF can achieve a current density of 100 mA/cm² at an overpotential of 198 mV in UOR process. The BiCoAl-LTH/NF was used as both the anode and cathode to construct a urea electrolysis system. A current density of 100 mA/cm² can be achieved with only a cell voltage of 1.65 V. Compared to conventional water electrolysis with the oxygen evolution reaction at the anode, the BiCoAl-LTH/NF catalyst can save 40% of energy in urea electrolysis for hydrogen production.