Designing electrocatalysts with high-performance for both reduction and oxidation reactions faces severe challenges. Here, the uniform and ultrasmall (~3.4 nm) high-entropy alloys (HEAs) Pt18Ni26Fe15Co14Cu27 nanoparticles are synthesized by a simple low-temperature oil phase strategy at atmospheric pressure. The Pt18Ni26Fe15Co14Cu27/C catalyst exhibits excellent electrocatalytic performance for hydrogen evolution reaction (HER) and methanol oxidation reaction (MOR). The catalyst shows ultrasmall overpotential of 11 mV at the current density of 10 mA cm−2, excellent activity (10.96 A mg−1Pt at −0.07 V vs. reversible hydrogen electrode) and stability in the alkaline medium. Furthermore, it is also the efficient catalyst (15.04 A mg−1Pt) ever reported for MOR in alkaline solution. Periodic DFT calculations confirm the multi-active sites for both HER and MOR on the HEA surface as the key factor for both proton and intermediate transformation. Meanwhile, the construction of HEA surfaces supplies the fast site-to-site electron transfer for both reduction and oxidation processes.

Coordination engineering can enhance the activity and stability of the catalyst in heterogeneous catalysis. However, the axial coordination engineering between different groups on the carbon carrier and molecular catalysts in the electrocatalytic carbon dioxide reduction reaction (CO 2 RR) has been studied rarely. Through coordination engineering strategy, a series of amino (NH 2 ), hydroxyl (OH), and carboxyl (COOH) groups functionalized carbon nanotubes (CNT) immobilized cobalt phthalocyanine (CoPc) catalysts are designed. Compared with no groups, OH groups and COOH groups, NH 2 groups can effectively change the coordination environment of the central metal Co, thereby significantly increasing the turnover frequency (TOF) (31.4 s −1 at −0.6 V vs. RHE, CoPc/NH 2 -CNT > CoPc/OH-CNT > CoPc/COOH-CN > CoPc/CNT). In the flow cell, the CoPc/NH 2 -CNT catalyst has high carbon monoxide (CO) selectivity at high current density (~ 100% at −225 mA•cm −2 , ~ 96% at −351 mA•cm −2 ). Importantly, the CoPc/NH 2 -CNT catalyst can operate stably for 100 h at 225 mA•cm −2 . Theoretical calculations reveal that CoPc/NH 2 -CNT catalyst is beneficial to the formation of COOH and desorption of CO, thus promoting CO 2 RR. This work provides an excellent platform for understanding the effect of coordination engineering on electrocatalytic performance and promotes a way to explore efficient and stable catalysts in other applications.

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A novel Ru-based high entropy oxide electrocatalyst RuNiMoCrFeOx/CNT was successfully synthesized, where the OER tends to proceed through the LOM on the high entropy surface, high entropy stabilizes the lattice oxygen to participate in the reaction.