Nickel-Cobalt Phosphide Terephthalic acid Nano-heterojunction as Excellent Bifunctional Electrocatalyst for Overall Water Splitting

Interface Engineering for Improved Large-Current Oxygen Evolution via Partial Phosphorization of Ce-MOF/NiCo-MOF Heterostructure

Interface engineering for electrocatalysts has proven to be an effective method for modulating electrocatalytic properties, yet a more efficient and straightforward strategy to construct a valid heterointerface for further enhancing interface effects is urgently needed for boosting oxygen evolution reactions (OER) at large current. Herein, a closely compacted heterostructure combining NiCo-metal-organic framework (MOF) and Ce-MOF is in situ formed through a one-step hydrothermal treatment, and partial phosphorization is employed to further enhance the interface effect between the newly formed urchin-shaped NiCoP shells and hexagonal rod-like Ce-MOF cores on nickel foam (NiCoP/Ce-MOF@NF). Experimental and theoretical results indicate that the heterogeneous NiCoP/Ce-MOF@NF, characterized by a more intensive interface rather than a simple physical mixture, generates an OER-beneficial electronic structure, significantly facilitates charge transfer and reaction kinetics, and creates a synergistically stable structure. The optimal NiCoP/Ce-MOF@NF exhibits remarkable electrocatalytic activity for OER, achieving an ultralow overpotential of 268 mV at a current density of 500 mA cm-2, and also delivers satisfactory large-current stability of up to 120 h. This work offers a novel approach for designing heterogeneous catalysts with strong interface effects for potential applications in industrial water electrolysis.

Ruthenium-Alloyed Iron Phosphide Single Crystal with Increased Fermi Level for Efficient Hydrogen Evolution

Transition metal phosphide alloying is an effective approach for optimizing the electronic structure and improving the intrinsic performance of the hydrogen evolution reaction (HER). However, obtaining 3d transition metal phosphides alloyed with noble metals is still a challenge owing to their difference in electronegativity, and the influence of their electronic structure modulated by noble metals on the HER reaction also remains unclear. In this study, we successfully incorporated Ru into an Fe₂P single crystal via the Bridgeman method and used it as a model catalyst, which effectively promoted HER. Hall transport measurements combined with first-principles calculations revealed that Ru acted as an electron dopant in the structure and increased the Fermi level, leading to a decreased water dissociation barrier and an improved electron-transfer Volmer step at low overpotentials. Additionally, the (21̅1) facet of Ru-Fe₂P was found to be more active than its (001) facet, mainly due to the lower H desorption barrier at high overpotentials. The synergistic effect of Ru and Fe sites was also revealed to facilitate H* and OH* desorption compared with Fe₂P. Therefore, this study elucidates the boosting effect of Ru-alloyed iron phosphides and offers new understanding about the relationship between their electronic structure and HER performance.