Renewable (electrical) energy from sources like photovoltaics and windmills, which are inherently intermittent, requires significant storage of the energy. Hydrogen(H₂) from electrochemical water splitting offers a nearly unlimited renewable resource for energy storage and bulk chemical processing. Platinum(Pt), although scarce, remains the archetypical electrocatalyst for acidic H₂ evolution. While several non-noble metal catalysts have been found, they all, except one, perform worse than Pt. Since 2013, many transition metal phosphides have been reported as possible replacements for Pt. Our group reported that one particular nickel phosphide phase, Ni₅P₄, is comparable to Pt in activity (geometrically) as well as corrosion resistant in both strong acid and alkali during electrocatalysis. Here, we will present comparative studies of the activity, efficiency and corrosion stability of five crystalline Ni_xP_y phases during electrocatalytic H₂ evolution.  Supported by Rutgers, NATCO and NSF-CBET/DOE.