Coherent Sub-Nanometer Interface between Crystalline and Amorphous Materials Boosts Electrochemical Synthesis of Hydrogen Peroxide

Highly Air-Stable N-Doped Two-Dimensional Violet Phosphorus with Atomically Flat Surfaces

Few-layer violet phosphorus (VP) shows excellent potential in optoelectronic applications due to its unique in-plane anisotropy and high mobility. However, the poor air stability of VP severely limits its practical applications. This article reports highly air-stable VP obtained by a two-step nitrogen plasma treatment where the nitrogen volume flow rate is controlled to coordinate physical etching and chemical doping. Specially, this plasma process can remove partial oxidations formed on the VP surface with barely etching to the intrinsic VP surface but efficiently incorporates nitrogen into VP, resulting in surface nitrogen-doped VP (N-VP) nanosheets with atomically smooth surfaces that exhibit excellent air stability. Atomic force microscopy images show that the N-VP nanosheet, nearing a monolayer thickness, maintained its surface morphology and flatness unchanged in ambient air for over 60 days. The improved stability of N-VP can be partly due to its atomically smooth surface, which reduces the number of active or oxidation sites. Further elucidation was made by density functional theory calculations, showing that this ultrastability may intrinsically be attributed to repairing P vacancies by N dopants. This research provides a feasible strategy for significantly enhancing the durability of VP.

A Coordination-Derived Cerium-Based Amorphous-Crystalline Heterostructure with High Electrocatalytic Oxygen Evolution Activity

The rational design of heterogeneous catalysts is crucial for achieving optimal physicochemical properties and high electrochemical activity. However, the development of new amorphous-crystalline heterostructures is significantly more challenging than that of the existing crystalline-crystalline heterostructures. To overcome these issues, a coordination-assisted strategy that can help fabricate an amorphous NiO/crystalline NiCeOx (a-NiO/c-NiCeOx) heterostructure is reported herein. The coordination geometry of the organic ligands plays a pivotal role in permitting the formation of coordination polymers with high Ni contents. This consequently provides an opportunity for enabling the supersaturation of Ni in the NiCeOx structure during annealing, leading to the endogenous spillover of Ni from the depths of NiCeOx to its surface. The resulting heterostructure, featuring strongly coupled amorphous NiO and crystalline NiCeOx, exhibits harmonious interactions in addition to low overpotentials and high catalytic stability in the oxygen evolution reaction (OER). Theoretical calculations prove that the amorphous-crystalline interfaces facilitate charge transfer, which plays a critical role in regulating the local electron density of the Ni sites, thereby promoting the adsorption of oxygen-based intermediates on the Ni sites and lowering the dissociation-related energy barriers. Overall, this study underscores the potential of coordinating different metal ions at the molecular level to advance amorphous-crystalline heterostructure design.