Mo Migration-Induced Crystalline to Amorphous Conversion and Formation of RuMo/NiMoO4 Heterogeneous Nanoarray for Hydrazine-Assisted Water Splitting at Large Current Density.

Manipulating the atomic structure of the catalyst and tailoring the dissociative water-hydrogen bonding network at the catalyst-electrolyte interface is essential for propelling alkaline hydrogen evolution reactions (HER) and hydrazine oxidation reaction (HzOR), but remains a great challenge. Herein, we constructed an advanced a-RuMo/NiMoO4/NF heterogeneous electrocatalysts with amorphous RuMo alloy nanoclusters anchored to amorphous NiMoO4 skeletons on Ni foam by a heteroatom implantation strategy. Theoretical calculations and in-situ Raman tests show that the amorphous and alloying structure of a-RuMo/NiMoO4/NF not only induces the directional evolution of interfacial H2O, but also lowers the d-band center (from -0.43 to -2.22 eV) of a-RuMo/NiMoO4/NF, the Gibbs free energy of hydrogen adsorption (ΔGH*, from -1.29 to -0.06 eV), and the energy barrier of HzOR (ΔGN2(g) = 1.50 eV to ΔGN2* = 0.47 eV). Profiting from these favorable factors, the a-RuMo/NiMoO4/NF exhibits excellent electrocatalytic performances, especially at large current densities, with an overpotential of 13 and 129 mV to reach 10 and 1000 mA cm-2 for HER. While for HzOR, it needs only -91 and 276 mV to deliver 10 and 500 mA cm-2, respectively. Further, the constructed a-RuMo/NiMoO4/NF||a-RuMo/NiMoO4/NF electrolyzer demands only 7 and 420 mV to afford 10 and 500 mA cm-2.

Piezoelectric Bilayer Nickel-Iron Layered Double Hydroxide Nanosheets with Tumor Microenvironment Responsiveness for Intensive Piezocatalytic Therapy.

Piezocatalytic therapy (PCT) based on 2D layered materials has emerged as a promising non-invasive tumor treatment modality, offering superior advantages. However, a systematic investigation of PCT, particularly the mechanisms underlying the reactive oxygen species (ROS) generation by 2D nanomaterials, is still in its infancy. Here, for the first time, biodegradable piezoelectric 2D bilayer nickel-iron layered double hydroxide (NiFe-LDH) nanosheets (thickness of ≈1.86 nm) are reported for enhanced PCT and ferroptosis. Under ultrasound irradiation, the piezoelectric semiconducting NiFe-LDH exhibits a remarkable ability to generate superoxide anion radicals, due to the formation of a built-in electric field that facilitates the separation of electrons and holes. Notably, the significant excitonic effect in the ultrathin NiFe-LDH system enables long-lived excited triplet excitons (lifetime of ≈5.04 µs) to effectively convert triplet O2 molecules into singlet oxygen. Moreover, NiFe-LDH exhibited tumor microenvironment (TME)-responsive peroxidase (POD)-like and glutathione (GSH)-depleting capabilities, further enhancing oxidative stress in tumor cells and inducing ferroptosis. To the best of knowledge, this is the first report on piezoelectric semiconducting sonosensitizers based on LDHs for PCT and ferroptosis, providing a comprehensive understanding of the piezocatalysis mechanism and valuable references for the application of LDHs and other 2D materials in cancer therapy.

Mott-Schottky Construction Boosted Plasmon Thermal and Electronic Effects on the Ag/CoV-LDH Nanohybrids for Highly-Efficient Water Oxidation.

Mott-Schottky construction and plasmon excitation represent two highly-efficient and closely-linked coping strategies to the high energy loss of oxygen evolution reaction (OER), but the combined effect has rarely been investigated. Herein, with Ag nanoparticles as electronic structure regulator and plasmon exciter, Ag/CoV-LDH@G nanohybrids (NHs) with Mott-Schottky heterojunction and notable plasmon effect are well-designed. Combining theoretical calculations with experiments, it is found that the Mott-Schottky construction modulates the Fermi level/energy band structure of CoV-LDH, which in turn leads to lowered d-band center (from -0.89 to -0.93), OER energy barrier (from 6.78 to 1.31 eV), and preeminent plasmon thermal/electronic effects. The thermal effect can offset the endothermic enthalpy change of OER, promote the deprotonation of *OOH, and accelerate electron transfer kinetics. Whereas the electronic effect can increase the density of charge carriers (from 0.70 × 1020 to 1.64 × 1020 cm-3), lower the activation energy of OER (from 30.3 to 17.7 kJ mol-1). Benefiting from these favorable factors, the Ag/CoV-LDH@G NHs show remarkable electrocatalytic performances, with an overpotential of 178 and 263 mV to afford 10 and 100 mA cm-2 for OER, respectively, and a low cell voltage of 1.42 V to drive 10 mA cm-2 for overall water splitting under near-infrared light irradiation.

Built-In Electric Field Boosted Overall Water Electrolysis at Large Current Density for the Heterogeneous Ir/CoMoO4 Nanosheet Arrays.

Advanced bifunctional electrocatalysts are essential for propelling overall water splitting (OWS) progress. Herein, relying on the obvious difference in the work function of Ir (5.44 eV) and CoMoO4 (4.03 eV) and the constructed built-in electric field (BEF), an Ir/CoMoO4/NF heterogeneous catalyst, with ultrafine Ir nanoclusters (1.8 ± 0.2 nm) embedded in CoMoO4 nanosheet arrays on the surface of nickel foam skeleton, is reported. Impressively, the Ir/CoMoO4/NF shows remarkable electrocatalytic bifunctionality toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), especially at large current densities, requiring only 13 and 166 mV to deliver 10 and 1000 mA cm-2 for HER and 196 and 318 mV for OER. Furthermore, the Ir/CoMoO4/NF||Ir/CoMoO4/NF electrolyzer demands only 1.43 and 1.81 V to drive 10 and 1000 mA cm-2 for OWS. Systematical theoretical calculations and tests show that the formed BEF not only optimizes interfacial charge distribution and the Fermi level of both Ir and CoMoO4, but also reduces the Gibbs free energy (ΔGH*, from 0.25 to 0.03 eV) and activation energy (from 13.6 to 8.9 kJ mol-1) of HER, the energy barrier (from 3.47 to 1.56 eV) and activation energy (from 21.1 to 13.9 kJ mol-1) of OER, thereby contributing to the glorious electrocatalytic bifunctionality.

Enhanced Electrocatalytic Water Oxidation by Interfacial Phase Transition and Photothermal Effect in Multiply Heterostructured Co9 S8 /Co3 S4 /Cu2 S Nanohybrids.

The rational design of advanced nanohybrids (NHs) with optimized interface electronic environment and rapid reaction kinetics is pivotal to electrocatalytic schedule. Herein, we developed a multiple heterogeneous Co9 S8 /Co3 S4 /Cu2 S nanoparticle in which Co3 S4 germinates between Co9 S8 and Cu2 S. Using high-angle annular-dark-field imaging and theoretical calculation, it was found that the integration of Co9 S8 and Cu2 S tends to trigger the interface phase transition of Co9 S8 , leading to Co3 S4 interlayer due to the low formation energy of Co3 S4 /Cu2 S (-7.61 eV) than Co9 S8 /Cu2 S (-5.86 eV). Such phase transition not only lowers the energy barrier of oxygen evolution reaction (OER, from 0.335 eV to 0.297 eV), but also increases charge carrier density (from 7.76×1014 to 2.09×1015  cm-3 ), and creates more active sites. Compared to Co9 S8 and Cu2 S, the Co9 S8 /Co3 S4 /Cu2 S NHs also demonstrate notable photothermal effect that can heat the catalyst locally, offset the endothermic enthalpy change of OER, and promote carrier migrate, reaction intermediates adsorption/deprotonation to improve reaction kinetics. Profiting from these favorable factors, the Co9 S8 /Co3 S4 /Cu2 S catalyst only requires an OER overpotential of 181 mV and overall water splitting cell voltage of 1.43 V to driven 10 mA cm-2 under the irradiation of near-infrared light, outperforming those without light irradiation and many reported Co-based catalysts.

Revealing the atomic-scale configuration modulation effect of boron dopant on carbon layers for H2O2 production.

This work reports an atomic-scale carbon layer configuration tuning strategy induced by a boron dopant. Through regulating the doping level of boron, it was found that the boron dopant not only favors carbon layer growth by strengthening the metallic state of the Ni core, but also enhances the abundance of pyrrolic N species and graphitization degree of carbon by tailoring the carbon/nitrogen atom configuration, thereby contributing to more active pyrrolic N/carbon sites and accelerated interface reaction dynamics. Consequently, the developed Ni@B,N-C catalyst achieves remarkable electrochemical H2O2 production performances with a high selectivity of 95.5% and a yield of 795 mmol g-1 h-1. In comparison with previous reports in which the boron dopant mainly acts as an electronic structure regulator, this study reveals the tuning effect of boron dopants on the atomic-scale carbon layer configuration, opening up a new avenue for the development of advanced catalysts.

Nanostructured metal chalcogenides confined in hollow structures for promoting energy storage.

The engineering of progressive nanostructures with subtle construction and abundant active sites is a key factor for the advance of highly efficient energy storage devices. Nanostructured metal chalcogenides confined in hollow structures possess abundant electroactive sites, more ions and electron pathways, and high local conductivity, as well as large interior free space in a quasi-closed structure, thus showing promising prospects for boosting energy-related applications. This review focuses on the most recent progress in the creation of diverse confined hollow metal chalcogenides (CHMCs), and their electrochemical applications. Particularly, by highlighting certain typical examples from these studies, a deep understanding of the formation mechanism of confined hollow structures and the decisive role of microstructure engineering in related performances are discussed and analyzed, aiming at prompting the nanoscale engineering and conceptual design of some advanced confined metal chalcogenide nanostructures. This will appeal to not only the chemistry-, energy-, and materials-related fields, but also environmental protection and nanotechnology, thus opening up new opportunities for applications of CHMCs in various fields, such as catalysis, adsorption and separation, and energy conversion and storage.

Amorphous Y(OH)3-promoted Ru/Y(OH)3 nanohybrids with high durability for electrocatalytic hydrogen evolution in alkaline media.

A novel Ru/Y(OH)3 nanohybrid with high activity and excellent durability for electrocatalytic hydrogen evolution in alkaline media was developed. The enhanced performance mainly arose from the amorphous Y(OH)3 scaffold that both facilitates water dissociation and enhances the structural stability of Ru/Y(OH)3 due to the strong interaction between Ru and Y(OH)3.