Enhanced electrocatalytic performance of CuxNi1-xS Nanoflakes for overall water splitting

•CuxNi1-xS nanosheets perform well in alkaline media for simultaneous hydrogen and oxygen evolution.•Electrocatalytic HER and OER activity with over potential of 152 mV and 189 mV are achieved.•Cu2+-doping modified electronic structure leads to accelerated flow of charges in electrochemical reaction.•Electrolysis cell shows higher current of 80 mA/cm2 at just 2.61 V with bifunctional electrocatalysis.