Hierarchical 2D/2D interface of nickel aluminum oxide and nickel aluminum layered double hydroxide nanoflowers: An efficient and robust electrocatalyt for overall water splitting

•2D/2D interfacial Ni and Al based nano-heterostructures was developed.•NAO/NA-LDH-NHS was competent for both HER and OER.•Enabled overall water splitting with good stability and viable to commercial catalyst.•Stainless steel electrodes were used to load NHS and acted as bifunctional electrocatalyst. Here, the highly effective and low cost bi-functional electrocatalyst with heterogeneous nanostructures was developed for overall water splitting. It means the nano-heterostructure (NHS) made up of nickel aluminum oxide/nickel aluminum layered double hydroxide (NAO/NA-LDH) nanoflowers loaded at 316 stainless steel (SSL) was explored. The formation of NAO/NA-LDH-NHS was studied by FE-SEM, XRD, HR-TEM, XPS and BET. The as-prepared Dahlia flower like hierarchical NHS electrocatalyst requires an outstanding low overpotential of 29 mV for HER and 230 mV for OER activity to attain the current density of 10 mA cm−2 and competitively outperformed than the individual counter parts such as NAO and NA-LDH. Also, the minimum Tafel slope values were obtained at NAO/NA-LDH-NHS loaded electrode such as 39 mV dec−1 and 38 mV dec−1 for HER and OER, respectively signifies the facile electron transfer ability and synergistic electrocatalytic activity toward HER and OER in alkaline medium. Besides, in two electrode system, the developed bi-functional electrocatalyst has firmly used to ease out the high-performance alkaline water electrolysis with a cell voltage of 1.51 V at 10 mA cm−2 to exceed the bench marking electrocatalyst such as Pt/C and RuO2 electrodes in overall water splitting. The Faradaic efficiency was calculated as 97% which inherently facilitates for efficient water electrolysis. Thus the prepared electrocatalyst has displayed an excellent robustness both at HER and OER studies and also in overall water splitting. Besides, in the present investigation, the metal oxides used as a substrate to grow the corresponding hydroxide is a new strategy to study the overall water splitting and other energy harnessing application. [Display omitted]