In order to realize industrial production of hydrogen through water splitting,it is essential to develop a cost-efficient and scalable approach to synthesize nonprecious electrocatalysts with sufficiently high ac-tivity and stability to replace commercial noble-metal-based electrocatalysts.Herein we synthesize cobalt phosphide nanoparticles dispersed within nitrogen-doped carbon nanotube network(CP@NCNT)via scal-able spray drying and thermal treatments.As a multifunctional electrocatalyst,the CP@NCNT hybrid de-livers outstanding activity for HER(in both acidic and alkaline electrolytes),OER and overall water split-ting.Remarkably,it shows an ultra-low overpotental of 94 mV to obtain 10 mA cm-2 in HER.It also demonstrates outstanding activity in overall water splitting,requiring only 1.619 V to deliver 10 mA cm-2 with more than 72 h'long-term stability.The combination of notable performance,multi-functionality and highly scalable spray-drying synthesis method enables this material as a novel and cost-efficient transition metal-based electrocatalysts for overall water splitting.