Nanostructured Wire-in-Plate Electrocatalyst for High-Durability Production of Hydrogen and Nitrogen from Alkaline Ammonia Solution

Electrocatalytic oxidation of ammonia provides a potential solution for on-board hydrogen supply for a fuel-cell vehicle. However, the lack of active, stable, and low-cost electrocatalysts restricts its application. Herein, we report a nanostructured catalyst of Cu2O wire-in-Ni­(OH)2 plate passivated by a thin CuO surface, which can stably electrolyze alkaline ammonia solution into hydrogen and nitrogen at a high current density of 80 mA cm–2 at room temperature. The improved performance is ascribed to the peculiar wire-in-plate nanostructure, which not only enhances the catalytic activity via a Ni–Cu synergistic interaction but also protects Cu2O from oxidation and dissolution in the electrolyte

Synergistic Effect of Titanate-Anatase Heterostructure and Hydrogenation-Induced Surface Disorder on Photocatalytic Water Splitting

Black TiO₂ obtained by hydrogenation has attracted enormous attention due to its unusual photocatalytic activity. In this contribution, a novel photocatalyst containing both a titanate–anatase heterostructure and a surface disordered shell was in situ synthesized by using a one-step hydrogenation treatment of titanate nanowires at ambient pressure, which exhibited remarkably improved photocatalytic activity for water splitting under simulated solar light. The as-hydrogenated catalyst with a heterostructure and a surface disordered shell displayed a high hydrogen production rate of 216.5 μmol·h^–1, which is ∼20 times higher than the Pt-loaded titanate nanowires lacking of such unique structure. The in situ-generated heterostructure and hydrogenation-induced surface disorder can efficiently promote the separation and transfer of photoexcited electron–hole pairs, inhibiting the fast recombination of the generated charge carriers. A general synergistic effect of the heterostructure and the surface disordered shell on photocatalytic water splitting is revealed for the first time in this work, and the as-proposed photocatalyst design and preparation strategy could be widely extended to other composite photocatalytic systems used for solar energy conversion

In Situ Formation of Disorder-Engineered TiO₂(B)-Anatase Heterophase Junction for Enhanced Photocatalytic Hydrogen Evolution

Hydrogenation of semiconductors is an efficient way to increase their photocatalytic activity by forming disorder-engineered structures. Herein, we report a facile hydrogenation process of TiO₂(B) nanobelts to in situ generate TiO₂(B)-anatase heterophase junction with a disordered surface shell. The catalyst exhibits an excellent performance for photocatalytic hydrogen evolution under the simulated solar light irradiation (∼580 μmol h^–1, 0.02 g photocatalyst). The atomically well-matched heterophase junction, along with the disorder-engineered surface shell, promotes the separation of electron–hole and inhibits their recombination. This strategy can be further employed to design other disorder-engineered composite photocatalysts for solar energy utilization

Coaddition of Phosphorus and Proton to Graphitic Carbon Nitride for Synergistically Enhanced Visible Light Photocatalytic Degradation and Hydrogen Evolution

Graphitic carbon nitride (g-C3N4) has attracted enormous attention in photocatalysis owing to its special structure and properties. The insufficient light absorption and fast charge-carrier recombination limit its further photocatalytic application. Herein, we report a facile approach to fabrication of the g-C3N4 modified simultaneously with phosphorus and proton by directly heating the mixture of urea phosphate (UP) and urea in air. The incorporation of the phosphorus atoms in g-C3N4 can significantly decrease the band gap, leading to the enhanced light absorption efficiency. Furthermore, UP can also introduce the protons to the structure of g-C3N4 from protonation. The protons can inhibit the recombination of the charge carriers and improve their utilization. The synergistic effect of the phosphorus doping and protonation in g-C3N4 results in the superior visible-light photocatalytic performance for both degradation of Rhodamine B (RhB) and H2 evolution from water splitting. We believe that our findings have a broad applicability to design efficient and novel g-C3N4-based photocatalysts

Hydrogenated Cagelike Titania Hollow Spherical Photocatalysts for Hydrogen Evolution under Simulated Solar Light Irradiation

We synthesized the hydrogenated cagelike TiO2 hollow spheres through a facile sacrificial template method. After the hydrogenation treatment, the disordered surface layer and cagelike pores were generated on the shell of the hollow spheres. The spheres exhibit a high hydrogen evolution rate of 212.7 ± 10.6 μmol h–1 (20 mg) under the simulated solar light irradiation, which is ∼12 times higher than the hydrogenated TiO2 solid spheres and is ∼9 times higher than the original TiO2 hollow spheres. The high activity results from the unique architectures and hydrogenation. Both the multiple reflection that was improved by the cagelike hollow structures and the red shift of the absorption edge that was induced by hydrogenation can enhance the ultraviolet and visible light absorption. In addition, the high concentration of oxygen vacancies, as well as the hydrogenated disordered surface layer, can improve the efficiency for migration and separation of generated charge carriers

RuO₂–CeO₂ Lattice Matching Strategy Enables Robust Water Oxidation Electrocatalysis in Acidic Media via Two Distinct Oxygen Evolution Mechanisms

The discovery of acid-stable and highly active electrocatalysts for the oxygen evolution reaction (OER) is crucial in the quest for high-performance water-splitting technologies. Herein, a heterostructured RuO2–CeO2 electrocatalyst was constructed by using a lattice-matching strategy. The interfacial Ru–O–Ce bridge structure provided a channel for electron transfer between Ru and Ce, creating a lattice stress that distorts the local structure of RuO2. The resulting RuO2–CeO2 catalyst exhibited attractive stability with negligible decay after 1000 h of the OER in 0.5 M H2SO4, along with high activity with an overpotential of only 180 mV at 10 mA cm–2. In situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS), in situ differential electrochemical mass spectrometry (DEMS), and density functional theory (DFT) calculations were used to reveal that the interface and noninterface RuO2 sites enabled an oxide path mechanism (OPM) and the enhanced adsorbate evolution mechanism (AEM-plus), respectively, during the OER. The simultaneous and independent OER pathways accessible by lattice matching guides improved electrocatalyst design for the OER in acidic media