Effect of current density and solution composition on current efficiency for the electrochemical reduction of benzaldehyde

This research deals with the effect of current density and benzaldehyde and ethanol concentrations on current efficiency for benzaldehyde reduction at the cathodes: a)-Raney-Ni; b)-a titanium substrate having an electrochemically deposited Ni92Mo8 alloy coating; c)-a titanium substrate having a Ni93Mo7 alloy coating produced by the plasma spraying process; d)-a cathode made from pressed electrogenerated Ni92.8Mo7.2 powder and e)-a zinc amalgam cathode Zn(Hg). Current efficiency increases with benzaldehyde concentration in the solution increasing from 0.4 mol dm-3 to 1.2 mol dm-3. The increase in current efficiency is due to the increased rate of the reaction of adsorbed benzol intermediates with water molecules. The increase in current density leads to a decrease in the cathodic current efficiency. The decrease is caused by the small effect of the cathodic over potential on the rate of the chemical reaction of benzol intermediates with water. As ethanol content in the solution increases, the cathodic current efficiency decreases.