Unveiling the contribution of catalytic particles to the electrochemical performance of a Pb-dispersed particle composite anode for nonferrous metal electrowinning

Incorporating oxygen evolution catalytic particles into the Pb matrix via a powder mixing-pressing-sintering process is an effective strategy to develop efficient lead-dispersed particle (Pb-DP) composite anodes for nonferrous metal electrowinning . Catalytic particles are demonstrated to significantly reduce the anodic potential of Pb-DP anodes. However, the intrinsic contribution of catalytic particles to the electrochemical performance of Pb-DP anodes remains obscure. Herein, Pb-DP anodes with different dispersed particles (chemically inert Si or C, catalytic Co 3 O 4 or MnCo 2 O 4 ) were prepared. The anodic potential, microstructure and phase composition of the oxide layer, and oxygen evolution behavior of these Pb-DP anodes were investigated and compared with those of the Pure-Pb anode (prepared without dispersed particles). The results showed that compared with the Pure-Pb anode, Pb-Si and Pb-C anodes present similar microstructures and phase compositions of the oxide layer. However, they exhibit a larger Tafel slope for the oxygen evolution reaction (OER). Although the incorporation of catalytic particles (Co 3 O 4 and MnCo 2 O 4 ) reduced the thickness and specific surface area of the oxide layer and inhibited PbO 2 growth, the presence of Co 3 O 4 and MnCo 2 O 4 significantly reduced the Tafel slope and charge transfer resistance ( R ct ) of the OER. Consequently, the anodic potentials of Pb-Co 3 O 4 and Pb-MnCo 2 O 4 are approximately 45 mV and 69 mV lower than that of Pure-Pb, respectively. It is demonstrated that the lower anodic potential of the Pb-Co 3 O 4 and Pb-MnCo 2 O 4 composite anodes originates from the catalytic activity of the dispersed particles rather than the physical effect of the dispersed particles.