The design and development of heterostructures have proven to be highly effective for hydrogen production and wastewater treatment due to their superior physicochemical properties compared to individual materials. In this study, an MgMn 2 O 4 /rGO heterostructure was synthesized via a simple ultrasonication method, exhibiting dual functionality toward both hydrogen evolution and photocatalytic degradation. The electrochemical HER activity of MgMn 2 O 4 /rGO was evaluated in an alkaline medium, where the optimized composite demonstrated a low overpotential of 135 mV at 10 mA cm −2 , a Tafel slope of 120 mV dec −1 , low polarization resistance, and remarkable long-term stability compared to pristine MgMn 2 O 4 . Furthermore, the synthesized nanocomposite effectively degraded malachite green dye, achieving a photocatalytic efficiency of 97.4% within 80 min, and retained 87.4% of its activity after five cycles, indicating excellent reusability. These results highlight that the MgMn 2 O 4 /rGO heterostructure is a promising bifunctional material for both photocatalytic wastewater treatment and electrocatalytic hydrogen generation. • MgMn 2 O 4 /rGO nanocomposite was prepared by the ultrasonication method. • MgMn 2 O 4 /rGO exhibits higher photocatalytic and electrochemical evolution. • Efficient charge transfer of MgMn 2 O 4 /rGO improved photocatalytic activity. • The prepared nanocomposite shows excellent stability in repeated experiments.
P et al. (Wed,) studied this question.