A practical milling route for highly dispersed and tunably loaded Pt in NiFe hydroxides as bifunctional water-splitting electrocatalysts

Noble metal-loaded layered hydroxides exhibit high efficiency in electrocatalyzing water splitting. However, their widespread use as bifunctional electrocatalysts is hindered by low metal loading, inefficient yield, and complex synthesis processes. In this work, platinum atoms were anchored onto nickel-iron layered double hydroxide/carbon nanotube (LDH/CNT) hybrid electrocatalysts by using a straightforward milling technique with K2PtCl6·6H2O as the Pt source. By adjusting the Pt-to-Fe ratio to 1/2 and 1/10, excellent electrocatalysts—Pt1/6-Ni2/3Fe1/3-LDH/CNT and Pt1/30-Ni2/3Fe1/3-LDH/CNT—were achieved with superior performance in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), outperforming the corresponding commercial Pt/C (20 wt%) and RuO2 electrocatalysts. The enhanced electrochemical performance is attributed to the modification of Pt's electronic structure, which exhibits electron-rich states for HER and electron-deficient states for OER, significantly boosting Pt's electrochemical activity. Furthermore, the simple milling technology for controlling Pt loading offers a promising approach for scaling up the production of electrocatalysts.