Construction of hydroxide pn junction for water splitting electrocatalysis

NiFe oxyhydroxide (NiFe-OH) has shown promising electrocatalytic oxygen evolution reaction (OER) activity. Here we suggest that the performance of NiFe-OH can be further enhanced by constructing pn junction. Using MnCo carbonate hydroxide (MnCo-CH)@NiFe-OH pn junction as a demonstration, we show that upon the construction of pn junction, the electrons flow from n-type NiFe-OH to MnCo-CH, which consequently generates a positively charged region on NiFe-OH. The density function theory calculation reveals that such an electronic property change results in an improved OER energetics. As a result, the MnCo-CH@NiFe-OH pn junction shows significantly enhanced OER performance that is -10 and -500 times that of NiFe-OH and MnCo-CH (in terms of the OER currents at the overpotential of 270 mV), respectively. Moreover, the pn junction also shows a greatly boosted hydrogen evolution reaction (HER) and therefore the overall water electrolysis activity that outperforms the Pt/C||RuO2 catalysts.

Automated summary

NiFe oxyhydroxide has promising OER activity, which can be further enhanced by constructing pn junction. The MnCo-CH@NiFe-OH pn junction shows significantly improved OER performance and HER activity, outperforming Pt/C||RuO2 catalysts.