Water electrolysis is considered to be an effective and promising technology to make high-purity H2,however,the relationship between anion species and catalytic performance of electrocatalysts is still not completely clear.Herein,we report an anion engineering strategy to tune electrocatalytic water oxidation activity for Co-based materials.Novel hierarchical Co-based oxide/selenide/phosphide (Co-A,A =O,Se,P)hexagrams have been chosen as model materials.Electrochemical results and theoretical calculations re-veal that the electron configuration,the electrical conductivity,and the oxidation potential of Co element in Co-A hexagrams could be moderated by the substitution of P atoms,which leads to the superior OER performance.Particularly,Co-P hexagram displays a low overpotential (η=269 mY) at j =10 mA/cm2 for the oxygen evolution reaction (OER) compared to Co-O hexagram (η =399 mV) and Co-Se hexa-gram (η=347 mY).This work is of great importance in understanding coordination atoms (O,Se and P)induced electrocatalytic properties of hierarchical Co-based materials.