King Fahd University of Petroleum & Minerals

Zinc oxide nanostructures (ZnO NSs), amongst the most extensively studied materials, are often decorated with noble metals in SERS studies to synergistically combine the advantages of both components. In this work, a simple and generic route has been developed to functionalize such ZnO NSs by gold nanoparticles (Au NPs) and silver nanoparticles (Ag NPs) simultaneously. The as-developed nanostructures, called hereafter Au-ZnO-Ag NSs, were found to be highly SERS-active compared to their counterpart, ZnO NSs. To understand the growth morphology and the mechanism behind strong SERS-activity, a series of specimens such as ZnO mists coated Ag nanostructures (i.e., ZnO-Ag NSs), Ag NPs and Au NPs on glass substrates have been collected and investigated. The morphology of each individual construct has been investigated along with their elemental composition by high resolution field emission scanning electron microscope (FESEM). It was evident that the core element (i.e., Ag NPs) of the Au-ZnO-Ag NSs, was diverse in size and shape and therefore the strongest enhancement factor (EF) was achieved. For ZnO-Ag NSs, ZnO was noticed to be small mists of diameter ca. 25 nm and deposited surrounding the Ag NPs. Such arrangement was speculated to facilitate charge transfer process. The chemical state and electronic structure of the elements in the Au-ZnO-Ag NSs were investigated by X-ray photoelectron spectroscopy (XPS) measurements. SERS-activity of Ag NPs, Au NPs, ZnO-Ag NSs and Au-ZnO-Ag NSs was confirmed using Rhodamine 6G (R6G) as Raman-active dyes with two different excitations. Two lasers such as 633 nm (i.e., 1.96 eV) and 532 nm (i.e., 2.33 eV) were used as excitations in SERS measurements. The EF of SERS was estimated for each construct and was found to be in the order of 10⁶. A plausible mechanism in terms of the charge transfer process has been demonstrated. It was speculated that ZnO NSs were influenced by both Ag NPs and Au NPs and contributed to a high EF. Such a versatile fabrication approach, along with a related investigation, is essential not only for unlocking the potential of SERS applications but also for revealing the underlying plasmonic properties of complex SERS-active nanostructures.

In this in-depth study, we developed a series of electrocatalysts by doping platinum (Pt) and palladium (Pd) into the zinc cobaltite system, yielding ZnPt_xPd_xCo_2-2xO₄@NF0≤x≤0.08 nanoelectrocatalyst. The noble metals Pt and Pd were introduced in controlled, low concentrations (< 8 %) to optimize the catalytic performance. The electrocatalysts were synthesized directly on nickel foam (NF) using an in situ hydrothermal method. Comprehensive characterization, including XRD, SEM, TEM, HR-TEM, EDX, and XPS, confirmed the cubic spinel oxide structure, morphology, and chemical composition of the catalysts. The optimized catalyst (x = 0.08) exhibited an impressive overpotential of 55 mV at -10 mA/cm², accompanied by a Tafel slope of 23 mV/dec. Density functional theory (DFT) calculations revealed that co-doping ZnCo₂O₄ with Pt and Pd enhances hydrogen evolution reaction (HER) activity through modification of the electronic structure, reduction of water dissociation barriers, and facilitation of synergistic adsorption across active sites. Specifically, while Pt sites exhibit strong H^∗ adsorption ( [Formula: see text] = -0.522 eV), this is counterbalanced by the nearly thermoneutral adsorption at adjacent O sites ( [Formula: see text] = -0.106 eV), resulting in a synergistic effect that mitigates potential active site poisoning on ZnPt_xPd_xCo_2-2xO₄. This complementary interaction enables sustained hydrogen production by balancing adsorption strengths across the catalyst surface. The presence of Pd and Co further contributes to this moderation, supporting efficient HER kinetics. These findings establish bimetallic doping as a promising strategy for optimizing electrocatalysts for green hydrogen production.

Seawater splitting has been considered an efficient technique for producing ultrapure and clean hydrogen.However, its large-scale production is limited by slow kinetics and the generation of undesirable, highly corrosive Cl₂/hypochlorite products.A revolutionary technique for generating hydrogen and valuable products involves replacing the CER/OER with thermodynamically more beneficial electro-oxidation reactions.These electro-oxidation reactions, which affect the loss of electrons at the anode, are more thermodynamically favorable than the conventional CER/OER.This strategy also includes other functionalities such as electro-synthesis (formic acid, acetone), electro-degradation of toxic chems. (hydrazine and urea sewage), crystalline NaCl production by inhibiting chlorine-related competitive processes (by introducing the common-ion effect), and increasing electrocatalyst durability by reducing the generation of toxic products (Cl₂/hypochlorite).This review explores new paradigms in energy-efficient hydrogen production via chem.-assisted electrocatalytic seawater splitting, focusing on challenges in seawater splitting, reductive chem. selection, advancements in electrocatalysts, and related electrochem. reaction mechanisms.To our knowledge, this will be the latest review on chem.-assisted energy-saving seawater splitting for hydrogen production