Multiple strategies of porous tetrametallene for efficient ethanol electrooxidation

Abstract

Due to the complexity of the ethanol oxidation reaction (EOR) process, it is difficult to balance the activity, stability and selectivity of the catalysts. Despite the remarkable progress of Pd-based studies, it is still difficult to solve these problems. Herein, a stable porous metallene structure is introduced and combined with OH adsorption effects, electronic effects and C–C bond cleavage site strategies to improve the EOR performance. The stable structure of metallene provides a large electrochemically active area, which further accelerates the mass transfer rate. After a series of composition and ratio optimizations, Pd₅₉W₈Rh₁₉Bi₁₄ porous metallene showed the highest mass activity (16.70 A mg_Pd⁻¹), and excellent C1 selectivity (65.41%), which was better than that of Pd₉₇W₃ (6.86 A mg_Pd⁻¹, 14.9%), Pd₇₂W₁₁Rh₁₇ (6.98 A mg_Pd⁻¹, 53.9%) and Pd₆₄W₁₇Bi₁₉ (8.09 A mg_Pd⁻¹, 48.13%). And after a 20 000 s stability test, the catalyst still maintains 32% of its initial activity. It was further demonstrated by electrochemical tests and in situ FTIR that Rh could effectively cleave the C–C bond of ethanol to C1 intermediates, while the oxygenophilic metal Bi could provide a large number of adsorbed OH_ad species, which facilitates the removal of strongly adsorbed C1 intermediates. By affecting the electronic structure of Pd, the adsorption energy of the poisoning substance on the catalyst surface is weakened. The rational use of various strategies to improve the performance of the catalyst is expected to be a solution for catalyst performance improvement in the alkaline EOR.