Unusual Sabatier principle on high entropy alloy catalysts for hydrogen evolution reactions

Abstract The Sabatier principle is widely explored in heterogeneous catalysis, graphically depicted in volcano plots. The most desirable activity is located at the peak of the volcano, and further advances in activity past this optimum are possible only by designing a catalyst that circumvents the limitations entailed by the Sabatier principle. In this work, by density functional theory calculations, we found that high entropy alloy (HEA) surface with spatially varying adsorption free energy of hydrogen (ΔGH*), where the active sites with strong adsorption adsorb hydrogen (H*) and other sites with weak adsorption release H* to produce H2, was against the “just right” (ΔGH* = 0 eV) in the Sabatier principle of hydrogen evolution reaction (HER). The Gaussian distribution [X ~ N(µ, σ2)] of ΔGH* on HEA was proposed as a descriptor, deriving an anomalous Sabatier principle, where a larger σ value results with µ = 0 eV results in a higher catalytic activity for HER. As a proof-of-concept, we synthesized a series of alloy systems, the PtFeCoNiCu HEA catalyst has the best catalytic performance for HER with an overpotential of 10.8 mV at -10 mA cm− 2 and 4.6 times higher intrinsic activity over the state-of-the-art Pt/C. Moreover, the calculated adsorption energy of C*, O*, and N* on HEAs also follows a Gaussian distribution, indicating the anomalous Sabatier principle can be extended to other related catalytic reactions.