Modulation of electronic structure caused by the coupling between Al, P modified NiO and Ru for boosting alkaline hydrogen evolution

Abstract

The development of clean energy is an effective strategy to address the energy crisis and climate environmental problems caused by excessive use of traditional fossil fuels, and designing advanced electrocatalysts for hydrogen evolution reactions (HER) is a meaningful challenge. In this study, Al-containing P-doped nickel oxide (NiAl_EO-P/CFP) was successfully prepared as a support for Ru by etching NiAl-layered double hydroxide (LDH) grown on carbon fiber paper (CFP) and a gas phase phosphating process. The coupling of Al and P modified NiO support with Ru (Ru-NiAl_EO-P/CFP) leads to the adjustment of the electronic structure. Al primarily functions as an electron donor, which redistributes electrons to neighboring Ru sites. P doping intensifies the concentration of electrons at Ru sites, promoting the formation of electron-deficient Al sites and electron-rich Ru sites, which reduce the high-energy barrier required for H-OH bond cleavage. In 1.0 M KOH, the Ru-NiAl_EO-P/CFP catalyst exhibited a competitive overpotential of 59.6 mV to drive a current density of 10 mA cm⁻² and possessed a small Tafel slope of 64.66 mV dec^-1 for HER. Notably, the P-O species from the oxidation state of P sites may effectively inhibit the deactivation of Ru, thus improving the durability of the catalyst. Therefore, the Ru-NiAl_EO-P/CFP demonstrated acceptable durability in the stability test of 20 h. This work provides a strategy to enhance the activity and durability of Ru by using modified transition metal oxides (TMOs), which is expected to be further used to develop advanced Ru-decorated TMOs catalysts for HER.