In-situ engineered heterostructured nickel tellur-selenide nanosheets for robust overall water splitting

High-performance electrocatalytic nanosheets of NiTe-NiSe for overall water splitting are synthesized by one-step in situ green processing of Ni-Fe foam using an ethylenediamine glycol system. The synergistic heterojunction of NiTe-NiSe dual-phase not only shows an excellent HER (76 mV vs j 10 , 437 mV vs j 1000 ) and OER (164 mV vs j 10 , 409 mV vs j 1000 ) performance, but also could operate stably for more than 100h at j 10 and j 100 . Driven with j 10 , the catalyst shows high generation efficiencies for H 2 (2.07 mmol h −1 ) and O 2 (0.90 mmol h −1 ), while the two-electrode cell voltage for delivering j 10 is only 1.49 V. • Green synthesis of nickel tellur-selenide nanosheet electrocatalysts for overall water splitting. • Unique laminated flower-like NiTe-NiSe structure with extra-large active surface area. • Dual-phase synergy improves interface electron transfer and intermediates adsorption. • Excellent bi-functional water splitting from low to industry-scale current densities. • The cell voltage for overall water splitting outperforms noble metal cell systems. Due to the large Gibbs free energy of metal telluride for hydrogen generation, tellurium (Te) based materials are rarely reported as catalysts for overall water splitting. Herein, a facile hydrothermal method is used to engineer the stacked flower-like NiTe-NiSe nanosheets, thus nearing the application of transition metal telluride in clean and renewable energy field. Thanks to the hollow flower-shaped catalyst assembled with nanosheets, the active surface area of the optimized electrode material is 20 times larger than that of a single NiTe/NFF or NiSe/NFF, causing low overpotentials for delivering a current density of 10 mA cm −2 ( j 10 ) in the hydrogen (HER, 76 mV) and oxygen (OER, 164 mV) evolution processes. The OER activity of NiTe-NiSe/NFF exceeds that of benchmarked RuO 2 even at moderate current densities above j 115 . Based on the results of experiments and DFT calculations, the unexpected high catalytic performance of NiTe-NiSe/NFF is attributed to the formed heterointerfaces and mismatched crystal lattice of NiTe, which effectively optimize the electronic structure through the phase synergy and cause a low adsorption free energy for the reactive intermediates.