Nitrate anion reduction in aqueous perchloric acid as an electrochemical probe of Pt{1 1 0}-(1 × 1) terrace sites

•Pt{1 1 0}-(1 × 1) site identified as most active for nitrate reduction.•Linear correlation between nitrate reduction current density and number of Pt{1 1 0}-(1 × 1) active sites.•Correlation may be used to estimate number of Pt{1 1 0}-(1 × 1) sites present at polycrystalline and nanoparticle Pt surfaces.•Pt{1 1 0} structure highly sensitive to ambient cooling conditions.•CO cooling favours formation of Pt{1 1 0}-(1 × 1).•Argon, nitrogen, hydrogen and oxygen cooling favour mixed (1 × 1)/(1 × 2) disordered phases.