Controllable Heteroatom Doping Effects of CrCo_2-P Nanoparticles: a Robust Electrocatalyst for Overall Water Splitting...

The effect of doping Cr on the electrocatalytic activity of Co₂P supported on carbon black (CrCo_2-P/CB) for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solution was investigated. A beneficial improvement in the performance of Co₂P toward HER and OER was discovered. For the HER at -200 mV overpotential, the turnover frequency (TOF) increases almost 6-fold from 0.26 to 1.52 electron site_Co^-1 s^-1 when Co₂P/CB has a small amount of Cr added to form Cr_0.2Co_1.8P/CB. Similarly, we estimate an increase from 0.205 to 0.585 electron site_Co^-1 s^-1 for the OER at 1.6 V for the same change in composition. With 10 atom % Cr doping, the Cr_0.2Co_1.8P/CB catalyst needed 226 mV overpotential to produce a cathodic current density of -100 A g_Co^-1 and 380 mV overpotential to produce an anodic current density of 100 A g_Co^-1. Based on both experimental results and theoretical calculations, the activity improvement results from optimization of the electronic properties of Co₂P after Cr doping.