Systematic Study of Oxygen Evolution Reaction Activity and Stability of Sn_nSb_mNb_lO_x Ternary Oxide-Supported IrO₂ Catalysts

Supporting IrO₂ with conductive oxides has proven to be a practical way to increase the conductivity of the catalyst layer as well as decrease the anode IrO₂ loading in proton exchange membrane electrolyzers. In this work, we proposed a high-throughput aerogel synthesis method to fabricate Sn–Sb–Nb ternary oxide supports. Their thermal stability, conductivity, and acidic stability were then systematically investigated; the results show that Nb addition decreases the ternary oxide’s conductivity by eliminating charge carriers. At the same time, Nb doping improves the thermal stability and increases the specific surface area of the ternary oxides; acidic stability is also increased with 5 at % Nb addition. IrO₂ nanoparticles are deposited on selected oxide aerogels via the Adams fusion method to synthesize 50 wt % IrO₂/Sn_nSb_mNb_lO_x catalysts. The catalytic performance and stability of catalysts with various supports were compared, revealing a boosted intrinsic activity than unsupported IrO₂. The optimal ternary oxide support employed in this work was Sn₈₀Sb₁₅Nb₅O_x. Its supported catalyst counterpart has a mass activity of 467 A g^–1 at 1.6 V (vs reversible hydrogen electrode) and a Tafel slope of 43.43 ± 0.43 mv dec^–1. Compared with other Nb doping amounts, 5 at % Nb catalyst dissolves Ir the least during the oxygen evolution reaction test, which we ascribed to Nb sacrifice. Moreover, the surface area of the supporting materials shows more remarkable influence on the resistance of the catalyst layer than their conductivity, which matters only when the supported catalysts have an approximate surface area. This finding also puts forward a strategy for the screening of supporting materials and provides valuable data for the design and prediction of supporting materials.