FeOOH-enhanced bifunctionality in Ni3N nanotube arrays for water splitting

Here we report the functional FeOOH as a cocatalyst to enhance excellent bifunctionality of the Ni3N catalyst, which demonstrate remarkable electrocatalytic activity for hydrogen evolution reaction (HER) and oxygen evolution reduction (OER) compared to the pristine Ni3N sample. Experimental data and theoretical calcinations demonstrate that the FeOOH facilitates surface adsorption and cleavage of OH−/H2O species and decrease the d-band center of active Ni species for optimizing the Gibbs free energy of intermediates. Furthermore, relatively vertical Ni3N nanotubes can promote the mass transport and electrons transfer as a main catalyst. The unusual synergistic effect in hybrid system with high density of heterointerface is contributed to the improvement of HER/OER catalytic performance. Specifically, the obtained FeOOH/Ni3N hybrid catalysts display excellent OER/HER performance with an overpotential of 244 mV/67 mV at 10 mA cm−2 in 1.0 M KOH, along with an applied potential of 1.58 V to boost overall water splitting at 10 mA cm−2. This simple and effective strategy may provide a new path to design the bifunctional catalysts and improve the catalytic performance for water splitting.