The role of the influence of sp³/sp² ratio for producing persulfate (S₂O₈²⁻) was investigated for the first time at boron doped diamond (BDD) electrodes with significant differences on diamond content. Results clearly pointed out that diamond with a very lower sp³/sp² ratio promotes an improvement on the production of S₂O₈²⁻ of about 50% at high current densities when compared with BDD with higher diamond content. From a practical application perspective, this novel result provides a guideline for designing diamond electrodes for environmental approaches.