Investigation of electrocatalytic pathway for hemoglobin toward nitric oxide by electrochemical approach based on protein controllable unfolding and in-situ reaction

► Electrocatalytic pathway of hemoglobin to NO is proved based on protein unfolding. ► Hemoglobin was controlled to be in an unfolded state to enhance sensing sensitivity. ► In-situ reaction was used to increase the stability of intermediate HbFe(II)-HN2O2. ► Catalytic mechanism of hemoglobin to NO is verified by density functional theory.