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Transition metal phosphides (TMPs) are a hopeful noble-metal-free catalysts for water splitting. In this study, we used a three-dimensional nanostructure on nickel substrate to easily synthesize a nickel–cobalt phosphide electrocatalyst (NixCoyP, x = 1, 1.5, 2; y = 1, 1.5, 2) through hydrothermal reaction and in situ phosphorylation. The NiCo1.5 P exhibited relatively excellent oxygen evolution activity performance, and it only needed the overpotentials of 123 mV for HER in 1 M KOH to perform the current densities of 10 mA cm−2. It is worth mentioning that the Ni2CoP exhibited better bifunctional electrocatalyst characteristics. As to water splitting, the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) require 197 and 253 mV overpotentials separately to provide a current density of 10 mA cm−2. Its relatively excellent electrochemical performance can be ascribed to the high-density sea urchin-like three-dimensional structure, which provides greater specific surface area and more active site. Besides, Ni2CoP also shows long-term durability lasting 80,000 s, and on this basis, there is no distinct deactivation. This work emphasizes that Ni2P and CoP play a vital role relative to the good activity of HER. Moreover, the unique morphology with self-supported structure provides a larger specific surface area, making it possible the exposure of higher amount of active sites for HER. These self-supported electrocatalysts that do not require a binder could also make the electrode more active and stable. This work, therefore, presents a strategy that is controllable and feasible strategy for the synthesis of bimetallic phosphides with unique morphology and high HER and OER activity.

CrFeNiTix (x = 0.2, 0.3, 0.4, 0.5, and 0.6 molar ratio) compositionally complex alloys were fabricated by vacuum arc melting to investigate the microstructure, hardness, and compressive properties. The results revealed that CrFeNiTix alloys consisted of the principal face-centered cubic (FCC) phase and body-centered cubic (BCC) solid solution, with an amount of (Ni, Ti)-rich hexagonal close-packed phase. CrFeNiTix alloys exhibited the typical dendrite. Ti0.2 and Ti0.3 alloys were composed of FCC and BCC solid solutions in the dendrite, as well as e (Ni3Ti) and R (Ni2.67Ti1.33) phases in the inter-dendrite, simultaneously. For Ti0.4, Ti0.5, and Ti0.6 alloys, (Fe, Cr)-rich solid solution separated out and e phase transformed into R phase gradually. Meanwhile, TEM analysis indicated that Ti0.4 alloy matrix consisted of the principal FCC phase containing (Ni, Ti)-rich intragranular nanoprecipitates. The hardness values of CrFeNiTix alloys were increased with the addition of Ti content and the high compressive strength of CrFeNiTix alloys was maintained, which was attributed to the solid solution strengthening and precipitation hardening.