“…[31] Furthermore, the peak of CoMoO 4 -N 2 is the sharpest and strongest, confirming the highest concentration of oxygen vacancies in CoMoO 4 -N 2 . The detailed oxygen vacancy concentration was calculated based on the EPR peak areas, [32,33] and the 2, 2, 6, 6-Tetramethylpiperidinooxy was used as the standard sample. The oxygen vacancy concentration in CoMoO 4 -N 2 , CoMoO 4 -Air, and CoMoO 4 -Precursor is 4.14 × 10 15 , 1.04 × 10 15 , and 2.74 × 10 15 spins/cm 3 , respectively.…”