“…4, the background of CV signals are observed with an evident decrease in the area enclosed in the sequence of: 1Pd/5La-CNT > 1Pd/5Ce-CNT > 1Pd/5Sm-CNT ≈ 1Pd/5Gd-CNT > 1Pd/5Er-CNT > 1Pd/5Yb-CNT>1Pd/ CNT. Rare-earth oxides are well known for their surface electron donor properties [54][55][56][57], which favors the enlargement of areas enclosed by CV curves, since the more redox active sites or electron donors on CNT, the larger capacitance and CV background are [58]. The sequence mentioned above is in tune with lanthanide contraction: basicity of rare-earth oxides, which is related to electron donor properties, declines with the contraction of rare-earth cation radius [59].…”