Layered transition metal selenides have garnered increased attention in recent times as non-noble metal bifunctional electrocatalysts for electrochemical water splitting. Tungsten diselenide @ tin diselenide heterostructures in the present study significantly increase the electrochemical performance of oxygen evolution reaction with a low overpotential of 250 mV at 10 mA cm−2 and high stability for 16 h (8.9 % loss), hydrogen evolution reaction with a low overpotential of 180 mV at 10 mA cm−2 with a 21.9% loss in 16 h. The overall water splitting using a lab-size electrolyzer shows a low cell voltage (1.52 V @ 10 mA cm−2) and high durability for 50 h (15.2% loss @ 10 mA cm−2 and 4.4% loss @ 50 mA cm−2). As a result, the heterostructures have demonstrated their ability to handle multiple challenges in energy conversion systems due to their unique properties. © 2022 Elsevier Inc.