Impact of solute concentration on the electrocatalytic conversion of dissolved gases in buffered solutions

摘要: Abstract To maintain local pH levels near the electrode during electrochemical reactions, use of buffer solutions is effective. Nevertheless, critical effects concentration on electrocatalytic performances have not been discussed in detail. In this study, two fundamental oxygen reduction reaction (ORR) and hydrogen oxidation (HOR), a platinum rotating disk are chosen as model gas-related aqueous reactions at various phosphate concentrations. Our detailed investigations revealed that kinetic limiting diffusion current densities for both ORR HOR logarithmically decrease with increasing solute ( log | j O R = − 0.39 c + 0.92 , H 0.35 0.73 ) . clarify physical aspects phenomenon, electrolyte characteristics addressed: concentration, gas solubility decrease, kinematic viscosity solution increase coefficient dissolved gases decrease. The simulated currents using aforementioned parameters match measured ones very well 0.43 0.99 0.40 0.54 accurately describing consequences concentration. These alterations properties associated universally applicable to other because purely determined by mass transfer gases.