Introducing carbon dots to NiFe LDH via a mild coprecipitation–aging method to construct a heterojunction for effective oxygen evolution

Abstract

Modified NiFe-layered double hydroxide (NiFe LDH) materials with a high oxygen evolution reaction (OER) performance make it possible to replace noble metal catalysts for widespread applications. Herein, we prepare a layered carbon dot (CD) composite catalyst (denoted as NiFe LDH@CDs) by a one-step coprecipitation method without heating or hydrothermal treatment. Due to the numerous functional groups of CDs, there were strong electron interactions between the two components. The CDs promoted rapid charge transfers and accelerated OER kinetics. Moreover, through binding with the CDs, the NiFe LDH@CDs formed a heterojunction structure, which could efficiently suppress photoelectron–hole recombination. Based on the beneficial factors, the Tafel slope of NiFe LDH@CDs-200 was 44.77 mV dec⁻¹, which further decreased to 38.44 mV dec⁻¹ under light even with a low content of CDs.