Seawater is the most plentiful natural resource we have on earth and new research looking for the alternative to the freshwater as seawater for hydrogen production by electrolysis. However, selective...
Amorphization of the support in single‐atom catalysts is a less researched concept for promoting catalytic kinetics through modulating the metal–support interaction (MSI). We modeled single‐atom ruthenium (RuSAs) supported on amorphous cobalt/nickel (oxy)hydroxide (Ru‐a‐CoNi) to explore the favorable MSI between RuSAs and the amorphous skeleton for the alkaline hydrogen evolution reaction (HER). Differing from the usual crystal counterpart (Ru‐c‐CoNi), the electrons on RuSAs are facilitated to exchange among local configurations (Ru‐O‐Co/Ni) of Ru‐a‐CoNi since the flexibly amorphous configuration induces the possible d–d electron transfer and medium‐to‐long range p–π orbital coupling, further intensifying the MSI. This embodies Ru‐a‐CoNi with enhanced water dissociation, alleviated oxophilicity, and rapid hydrogen migration, which results in superior durability and HER activity of Ru‐a‐CoNi, wherein only 15 mV can deliver 10 mA cm−2, significantly lower than the 58 mV required by Ru‐c‐CoNi.
The exact understanding for each promotional role of cation and anion vacancies in bifunctional water splitting activity will assist in the development of an efficient activation strategy of inert catalysts. Herein, systematic first-principles computations demonstrate that the synergy of anion-oxygen and cation-manganese vacancies (V O and V Mn ) in manganese dioxide (MnO 2 ) nanosheets results in abnormal local lattice distortion and electronic modulation. Such alterations enrich the accessible active centers, increase conductivity, enhance the water dissociation step, and favor intermediate adsorption-desorption, consequently promoting HER and OER kinetics. As proof of concept, robust electrocatalysts, MnO 2 ultrathin nanosheets doped with dual vacancies (DV-MnO 2 ) are obtained via a maturely chemical strategy. Detailed characterizations confirm the cation vacancies-V Mn contribute to enhanced conductivity and anion vacancies-V O enrich the active centers with optimized local electronic configurations, consistent with the simulative predictions. As expected, DV-MnO 2 exhibits exceptional bifunctionality with the strong assistance of synergetic dual vacancies which act as abundant "hot spots" for active multiple intermediates. Leading to a lower cell voltage (1.55 V) in alkali electrolyte is required to reach 10 mA cm −2 for the overall water splitting system. These atomic-level insights on synergetic DV can favor the development of activating strategy from inert electrocatalysts.
Effective charge separation and rapid transport of photogenerated charge carriers without self-oxidation in transition metal dichalcogenide photocatalysts are required for highly efficient and stable hydrogen generation. Here, we report that a molecular junction as an electron transfer path toward two-dimensional rhenium disulfide (2D ReS 2 ) nanosheets from zero-dimensional titanium dioxide (0D TiO 2 ) nanoparticles induces high efficiency and stability of solar hydrogen generation by balanced charge transport of photogenerated charge carriers. The molecular junctions are created through the chemical bonds between the functionalized ReS 2 nanosheets (e.g., −COOH groups) and −OH groups of two-phase TiO 2 (i.e., ReS 2 −C 6 H 5 C(O)− O−TiO 2 denoted by ReS 2 −BzO−TiO 2 ). This enhances the chemical energy at the conduction band minimum of ReS 2 in ReS 2 −BzO−TiO 2 , leading to efficiently improved hydrogen reduction. Through the molecular junction (a Z-scheme charge transfer path) in ReS 2 −BzO−TiO 2 , recombination of photogenerated charges and self-oxidation of the photocatalyst are restrained, resulting in a high photocatalytic activity (9.5 mmol h −1 per gram of ReS 2 nanosheets, a 4750-fold enhancement compared to bulk ReS 2 ) toward solar hydrogen generation with high cycling stability of more than 20 h. Our results provide an effective charge transfer path of photocatalytic TMDs by preventing self-oxidation, leading to increases in photocatalytic durability and a transport rate of the photogenerated charge carriers.
Chiral nanomaterials have attracted increasing attention due to their versatile optical properties. Although circularly polarized (CP) light can serve as an inducer, it has negligible effects because of the short lifetime of the plasmonic states. Here, we propose that the site-selective chirality regulation on the morphology of cysteine (cys) amino acid-assisted chiral gold nanoparticles (cys-chiral AuNPs) can be realized through CP light irradiation. This can result in the increased or decreased circular dichroism (CD) signal intensity. The site-selective growth mechanism of the cys-chiral AuNPs is elucidated with light–matter interactions through the opposite rotation of right(R)/left(L) CP light. The site-selective chirality growth of the cys-chiral AuNPs is ascribed to the morphology evolution induced by the synergy of cys and R/L-CP light, which is clearly analyzed and elucidated with high CD intensities. This work provides a promising alternative strategy to produce high-chirality nanomaterials that can be applied in biomedicine and enantiomer photocatalytic reaction.
Efficient transition metal oxide electrocatalysts for the alkaline hydrogen evolution reaction (HER) have received intensive attention to energy conversion but are limited by their sluggish water dissociation and unfavorable hydrogen migration and coupling. Herein, systematic density functional theory (DFT) predicts that on representative NiO, the hydroxylation (OH–) and heterointerface coupled with metallic Cu can respectively reduce the energy barrier of water dissociation and facilitate hydrogen spillover. Motivated by theoretical predictions, we subtly designed a delicate strategy to realize the electrochemical OH– modification in KOH with moderate concentration (HOM-NiO) and to channel rapid hydrogen spillover at the heterointerface of HOM-NiO and Cu, ensuring an enhanced HER kinetic. This HOM-NiO/Cu is systematically investigated by in situ XAS and electrochemical simulations, verifying its extraordinary merits for HER including the enhanced water dissociation, alleviated oxophilicity that is advantageous for consecutive adsorptions of water, and accelerated hydrogen spillover, thereby exhibiting superb HER activity with 33 and 310 mV overpotentials at the current densities of 10 and 1000 mA cm–2 in 1.0 M KOH, outperforming the Pt/C. This study might provide a reasonable strategy for the functionalized design of superior electrocatalysts.
The construction and regulation of heterogeneous interfaces are beneficial to improve solar light harvesting and photocharge separation of hybrid BiOCl-based photocatalysts, which are attributed to the synergistic effects that originate from the integrated interaction between disparate components. With the rapid development of synthetic technologies, hybrid BiOCl-based micro-/nanostructures with diversified components, morphologies, and sizes have been well prepared. Moreover, hybrid BiOCl-based photocatalysts have presented a promising potential for various photocatalytic applications, such as organic pollutant degradation, hydrogen production, NO removal, CO2 reduction, heavy metal ion detection, disinfection, nitrogen fixation, and alcohol oxidation. Previously, several review articles have mainly summarized the advances made in synthetic methods, morphological control, modification strategies, and applications of the bare BiOCl micro-/nanostructures. However, a comprehensive overview based on the type of species and the corresponding correlations between microstructures, performances, as well as photocatalytic mechanisms has been less reported for hybrid BiOCl-based photocatalysts so far. Therefore, a comprehensive understanding of the basic theory and research progress of hybrid BiOCl-based photocatalysts is imperative. This review aims to provide an overview of the important advances made in eight types of hybrid BiOCl-based photocatalysts, including metal/BiOCl, metal oxide/BiOCl, metal sulfide/BiOCl, BiOX (X = Cl, Br, I)/BiOCl, AgX (X = Cl, Br, I)/BiOCl, organics/BiOCl, carbon/BiOCl, and other BiOCl-based multicomponents. In each classification, the synthetic methods, modification strategies, relationships between interfacial microstructures, and enhanced performances are discussed based on some typical examples. Additionally, some scientific issues and potential directions are also given. Hopefully, this review paper will provide a useful reference for researchers currently focusing on exploring new BiOCl-based photocatalysts.
Surface heterojunctions were constructed in ZnO mesocrystals with co-exposed curved (101̄1) and flat (0001̄) surfaces and greater photocatalytic dye degradation was achieved compared to that of ZnO nanocrystals.
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