Charge state of steps on anatase TiO2(1 0 1) at 78 K by AFM/KPFM

•Four different steps on the anatase TiO2 (101) surface were investigated by AFM/KPFM.•A higher charge state in step B challenges the conventional belief.•A new step, step B II, is proposed and demonstrated to exhibit higher charge states.•The proposed model is also in line with traditional results that the charge state of step C is higher than step B I.•The O atoms at the step edges act as the primary electron donors.