The Construction\nof Face-to-Face Combination between\nNiFe-layered Double Hydroxide Nanosheets and Monolayer rGO for Efficient\nWater Splitting and Oxygen Reduction

Developing cost-effective and efficient electrocatalysts\nis essential\nfor advancing a green energy future. Herein, a NiFe-layered double\nhydroxide loaded on reduced graphene oxide (NiFe-LDHs@rGO) hybrid\nwas synthesized using a straightforward three-step process involving\nexfoliation tearing, electrostatic self-assembly, and chemical reduction.\nThe face-to-face packing and ultrathin exfoliation enable strong heterogeneous\ninteractions, fully harnessing the potential of these complementary\ntwo-dimensional counterparts. Consequently, the resultant catalyst\ndisplays outstanding oxygen evolution reaction (OER) catalytic activity\nand stability, whose overpotential is as low as 241 mV at 30 mA cm<sup>–2</sup> and 255 mV at 50 mA cm<sup>–2</sup> with a\nlow Tafel slope of 62.1 mV dec<sup>–1</sup>. Both the experimental\nresults and density functional theory (DFT) calculations reveal that\nthe face-to-face assembly strengthens the electronic interactions\nbetween NiFe-LDHs and rGO, which effectively modulates the d-band\ncenter of Ni and Fesites and improves the reaction kinetics for OER.\nMoreover, the resultant NiFe-LDHs@rGO hybrids exhibit excellent multifunctional\ncatalytic performance. Its hydrogen evolution reaction (HER) activity\nis endowed by Fe-site of NiFe-LDHs and defect states rGO and achieves\na low voltage of 1.68 V to drive a current density of 10 mA cm<sup>–2</sup> for overall water splitting. The face-to-face heteroassembly\nalso imparts NiFe-LDHs@rGO with superior oxygen reduction reaction\n(ORR) activity, with a half-wave potential of 0.70 V and a limiting\ncurrent density of 4.2 mA cm<sup>–2</sup>. Its ORR primarily\nfollows a four-electron transfer pathway with a minor contribution\nfrom a two-electron process. This study establishes the groundwork\nfor optimizing two-dimensional heterogeneous interfaces in LDH@carbon-based\nmaterials for advanced energy conversion.