Bifunctional Nd2Se3–Mn2O3 heterostructure nanospheres for enhanced alkaline water splitting via interface engineering

Abstract

The advancement of high-efficiency, durable, and inexpensive catalysts is essential for electrocatalytic water electrolysis to gain sustainable hydrogen energy. Catalysts based on noble metals (Pt, Pd for HER and Ir, Ru for OER) are efficient and benchmark towards water electrolysis, but high cost, scarcity, and lower stability prevent their applicability for industrial application. Up to now, rare earth/transition metal catalysts are still not more efficient and durable for water electrolysis. Herein, we report a Nd₂Se₃–Mn₂O₃ heterojunction assembled on stainless steel (SS) using a hydrothermal method to ameliorate the properties of electrocatalysts via interface engineering for HER, OER, and overall water splitting. Under comparison with two pure electrocatalysts (Nd₂Se₃ and Mn₂O₃), the full water splitting performance is checked in 3 and 2-electrolysis systems using the alkaline medium. Here, different physical characterization like XRD and TEM/EDX showed that the strong combination of two materials (Nd₂Se₃ and Mn₂O₃) leads to the structural reconstruction of precursor and spherical formation with an increasing number of disordered pores and active sites. Besides, XPS confirmed the strong electronic coupling, which enhances the adsorption of hydrogen atoms on the catalyst surface compared to pure ones. At 10 mA cm⁻², Nd₂Se₃–Mn₂O₃ delivers the smallest overpotential of 260 and 121 mV for OER and HER, indicating that coupling effects of Nd₂Se₃ and Mn₂O₃ are responsible for boosting the catalytic performances. The effect of small charge transfer resistance and large surface area for HER-OER about bifunctional electrocatalysts is confirmed using EIS and C_dl. Furthermore, an assembled Nd₂Se₃–Mn₂O₃//Nd₂Se₃–Mn₂O₃ device in a 2-electrode electrolyzer exhibited a cell voltage of 1.47 V along with excellent stability of 96 h at 10 mA cm⁻² for overall water splitting. This work paves the way for regulating the interface effect of bifunctional catalysts through heterojunctions to develop efficient and durable electrocatalysts.