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Rare earth (RE) elements are attractive for spin-magnetic modulation due to their unique 4f electron configuration and strong orbital couplings. Alloying RE with conventional 3d transition-metal (TM) is promising for the fabrication of advanced spin catalysts yet remains much difficulties in preparation, which leads to the mysteries of spin-magnetic effect between RE and 3d TM on catalysis. Here we define a solid-phase synthetic protocol for creating RE-3d TM-noble metal integrated intraparticle heterostructured nanoalloys (IHAs) with distinct Gd and Co interface within the entire Rh framework, denoted as RhCo-RhGd IHAs. They exhibit interface-triggered antiferromagnetic interaction, which can induce electron redistribution and regulate spin polarization. Theoretical calculations further reveal that active sites around the heterointerface with weakened spin polarization optimize the adsorption and dissociation of H2O, thus promoting alkaline hydrogen evolution catalysis. The RhCo-RhGd IHAs show a small overpotential of 11.3 mV at 10 mA cm-2, as well as remarkable long-term stability, far superior to previously reported Rh-based catalysts.
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π frameworks, defined as a type of porous supramolecular materials weaved from conjugated molecular units by π-π stacking interactions, provide a new direction in photocatalysis. However, such examples are rarely reported. Herein, we report a supramolecular-nanocage-based π framework constructed from a photoactive Cu(I) complex unit. Structurally, 24 Cu(I) complex units stack together through π-π stacking interactions, forming a truncated octahedral nanocage with sodalite topology. The inner diameter of the nanocage is 2.8 nm. By sharing four open faces, each nanocage connects with four equivalent ones, forming a 3D porous π framework (π-2). π-2 shows good thermal and chemical stability, which can adsorb CO2, iodine, and methyl orange molecules. More importantly, π-2 can serve as a photocatalyst for hydrogen evolution reaction. With ultrafine Pt subnanometer particles (0.9±0.1 nm) incorporated into the nanocages as a co-catalyst, the hydrogen evolution rate reaches a record-high value of 517551 µmol/gPt/h in the absence of any additional photosensitizers. The high photocatalytic activity can be ascribed to the ultrafine size of the Pt particles, as well as the fast electron transfer from π-2 to the highly active Pt upon illumination. π-2 represents the unique stable supramolecular-cage-based π framework with excellent photocatalytic activity.
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Metal clusters, due to their small dimensions, contain a high proportion of surface atoms, thus possessing a significantly improved catalytic activity compared with their bulk counterparts and nanoparticles. Defective and modified carbon supports are effective in stabilizing metal clusters, however, the synthesis of isolated metal clusters still requires multiple steps and harsh conditions. Herein, we develop a C60 fullerene-driven spontaneous metal deposition process, where C60 serves as both a reductant and an anchor, to achieve uniform metal (Rh, Ir, Pt, Pd, Au and Ru) clusters without the need for any defects or functional groups on C60. Density functional theory calculations reveal that C60 possesses multiple strong metal adsorption sites, which favors stable and uniform deposition of metal atoms. In addition, owing to the electron-withdrawing properties of C60, the electronic structures of metal clusters are effectively regulated, not only optimizing the adsorption behavior of reaction intermediates but also accelerating the kinetics of hydrogen evolution reaction. The synthesized Ru/C60-300 exhibits remarkable performance for hydrogen evolution in an alkaline condition. This study demonstrates a facile and efficient method for synthesizing effective fullerene-supported metal cluster catalysts without any pretreatment and additional reducing agent.
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The development of electrocatalysts with low cost, high efficiency, and long-term durability is crucial for advancing green hydrogen production. Transition metal phosphides (TMPs) have been proved to be efficient electrocatalyst, while the improvement in the performance and durability of the TMPs remains a big challenge. Employing atmospheric pressure chemical vapor deposition (APCVD) and phosphorization, FeP/Ti electrodes are fabricated featuring controllable oxygen ingredients (O-FeP/Ti). This manipulation of oxygen content fine-tunes the electronic structure of the catalyst, resulting in improved surface reaction kinetics and catalytic activity. The optimized O-FeP-400/Ti exhibits outstanding HER activity with overpotentials of 142 and 159 mV at -10 mA cm-2 in 0.5 M H2SO4 and 1 M KOH, respectively. Notably, the obtained O-FeP/Ti cathode also displays remarkable durability of up to 200 h in acidic electrolyte with surface topography remaining intact. For the first time, the low-valence titanium oxide (Ti3O) interlayer is identified in the composite electrode and ascribed for the superior connection between Ti substrate and the surface O-FeP catalyst, as supported by experimental results and density functional theory (DFT) analysis. This work has expanded the potential applications of transition metal phosphides (TMPs) as a cost-effective, highly efficient and durable catalyst for water splitting.
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Solar-powered seawater production of clean hydrogen fuel is highly prospective. In this work, Ni3C/Mn0.5Cd0.5S (NCMCS) Schottky junctions with excellent visible-light correspondence and photogenerated carrier separation properties are constructed using electrostatic attraction. The material achieves a hydrogen evolution rate of 6472.9 µmol h-1 g-1 in simulated seawater, which is 11 times higher than that of a single Mn0.5Cd0.5S (MCS). More attractively, the composite exhibits excellent hydrogen evolution rates in natural river water, groundwater and tap water, with significantly enhanced practical applicability. The underlying hydrogen evolution mechanism was extrapolated from a combination of experimental and theoretical calculations. The present work provides a low-cost and efficient hydrogen evolution photocatalyst for practical application, which can help promote the efficient conversion of solar-hydrogen energy.
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Realization of the full potential of single-atom photoelectrocatalysts in sustainable energy generation requires careful consideration of the design of the host material. Here, a comprehensive methodology for the rational design of photoelectrocatalysts using anodic titanium dioxide (TiO2) nanofilm as a model platform is presented. The properties of these nanofilms are precisely engineered to elucidate synergies across structural, chemical, optoelectronic, and electrochemical properties to maximize the efficiency of the hydrogen evolution reaction (HER). These findings clearly demonstrate that thicker TiO2 nanofilms in anatase phase with pits on the surface can accommodate single-atom platinum catalysts in an optimal configuration to increase HER performance. It is also evident that the electrolyte temperature can further enhance HER output through thermochemical effect. A judicious design incorporating all these factors into one system gives rise to a ten-fold HER enhancement. However, the reusability of the host photoelectrocatalyst is limited by the leaching of the Pt atom, worsening HER. Density-functional theory calculations have provided insights into the mechanism underlying the experimental observations in terms of moderate hydrogen adsorption and enhanced gas generation. This improved understanding of the critical factors determining HER performance in a model photoelectrocatalyst paves the way for future advances in scalable and translatable photoelectrocatalyst technologies.
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To take the pronounced issue of recombination among photogenerated electrons and holes in the photocatalytic reaction, we report a WC/CaIn2S4 Schottky heterojunction photocatalyst using a straightforward one-step hydrothermal method and applied it for the enhanced hydrogen evolution reaction in photocatalysis. A stable Schottky energy barrier can be formed by closely connecting the metal-like WC with the n-type semiconductor CaIn2S4, accelerating the migration of photogenerated carriers. Meanwhile, WC can lower the overpotential for hydrogen evolution, leading to a notable enhancement in the photocatalytic hydrogen evolution rate. The hydrogen evolution rate of the optimal WC/CaIn2S4 Schottky heterojunction photocatalyst WCIS1:1 was approximately 2.3 times higher than that of Pt-loaded photocatalyst CIS+Pt. This study delves into the application significance of the Schottky heterojunction principle in the photocatalytic hydrogen production reaction. Furthermore, this study provides a novel approach to replacing noble metal Pt with metal-like WC in the field of photocatalytic hydrogen evolution.
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An efficient and facile water dissociation process plays a crucial role in enhancing the activity of alkaline hydrogen evolution reaction (HER). Considering the intricate influence between interfacial water and intermediates in typical catalytic systems, meticulously engineered catalysts should be developed by modulating electron configurations and optimizing surface chemical bonds. Here, a high-entropy double perovskite (HEDP) electrocatalyst La2(Co1/6Ni1/6Mg1/6Zn1/6Na1/6Li1/6)RuO6, achieving a reduced overpotential of 40.7 mV at 10 mA cm-2 and maintaining exemplary stability over 82 h in a 1 m KOH electrolyte is reported. Advanced spectral characterization and first-principles calculations elucidate the electron transfer from Ru to Co and Ni positions, facilitated by alkali metal-induced super-exchange interaction in high-entropy crystals. This significantly optimizes hydrogen adsorption energy and lowers the water decomposition barrier. Concurrently, the super-exchange interaction enhances orbital hybridization and narrows the bandgap, thus improving catalytic efficiency and adsorption capacity while mitigating hysteresis-driven proton transfer. The high-entropy framework also ensures structural stability and longevity in alkaline environments. The work provides further insights into the formation mechanisms of HEDP and offers guidelines for discovering advanced, efficient hydrogen evolution catalysts through super-exchange interaction.
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The electrocatalytic performance of a Fe65Co10Si12.5B12.5 Fe-based compounds toward alkaline hydrogen evolution reaction (HER) is enhanced by dealloying. The dealloying process produced a large number of nanosheets on the surface of NS-Fe65Co10Si12.5B12.5, which greatly increased the specific surface area of the electrode. When the dealloying time is 3 h, the overpotential of NS-Fe65Co10Si12.5B12.5 is only 175.1 mV at 1.0 M KOH and 10 mA cm-2, while under the same conditions, the overpotential of Fe65Co10Si12.5B12.5 is 215 mV, which is reduced. In addition, dealloying treated electrodes also show better HER performance than un-dealloying treated electrodes. With the increase in Co doping amount, the overpotential of the hydrogen evolution reaction decreases, and the hydrogen evolution activity is the best when the addition amount of Co is 10%. This work not only provides a basic understanding of the relationship between surface activity and the dealloying of HER catalysts, but also paves a new way for doping transition metal elements in Fe-based electrocatalysts working in alkaline media.
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This study presents the synthesis, structural characterization, and evaluation of the photocatalytic performance of two novel one-dimensional (1D) lead(II) bromide hybrids, [Co(2,2'-bpy)3][Pb2Br6CH3OH] (1) and [Fe(2,2'-bpy)3][Pb2Br6] (2), synthesized via solvothermal reactions. These compounds incorporate transition metal complex cations as structural directors, contributing to the unique photophysical and photocatalytic properties of the resulting materials. Single-crystal X-ray diffraction analysis reveals that both compounds crystallize in monoclinic space groups with distinct 1D lead bromide chain configurations influenced by the nature of the complex cations. Optical property assessments show band gaps of 3.04 eV and 2.02 eV for compounds 1 and 2, respectively, indicating their potential for visible light absorption. Photocurrent measurements indicate a significantly higher electron-hole separation efficiency in compound 2, correlated with its narrower band gap. Additionally, photocatalytic evaluations demonstrate that while both compounds degrade organic dyes effectively, compound 2 also exhibits notable hydrogen evolution activity under visible light, a property not observed in 1. These findings highlight the role of metal complex cations in tuning the electronic and structural properties of lead(II) bromide hybrids, enhancing their applicability in photocatalytic and optoelectronic devices.
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Photocatalytic H2 evolution technology is regarded as a promising and green route for the urgent requirement of efficient H2 production. At present, low efficiency is a major bottleneck that limits the practical application of photocatalytic H2 evolution. The construction of high-activity photocatalysts is highly crucial for achieving advanced hydrogen generation. Herein, a new S-scheme FeS2@ZnIn2S4 (FeS2@ZIS) heterostructure as the photocatalyst was developed for enhanced photocatalytic H2 evolution. Density function theory (DFT) calculation results strongly demonstrated that FeS2@ZIS generates a giant interface electric field (IEF), thus promoting the separation efficiency of photogenerated charge carriers for efficient visible-light-driven hydrogen evolution. At optimal conditions, the H2 production rate of the 8%FeS2@ZIS is 5.3 and 3.6 times higher than that of the pure FeS2 and ZIS, respectively. The experimental results further indicate that the close contact between FeS2 and ZIS promotes the formation of the S-scheme heterojunction, where the interfacial charge transfer achieves spatial separation of charge carriers. This further broadens the light absorption range of the FeS2@ZIS and improves the utilization rate of photogenerated charge carriers. This work thus offers new insights that the FeS2-based co-catalyst can enrich the research on S-scheme heterojunction photocatalysts and improve the transfer and separation efficiency of photogenerated carriers for photocatalytic hydrogen production.
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Hydrogen has garnered considerable attention as a promising energy source for addressing contemporary environmental degradation and energy scarcity challenges. Electrocatalytic water splitting for hydrogen production has emerged as an environmentally friendly and versatile method, offering high purity. However, the development of cost-effective electrocatalytic catalysts using abundant and inexpensive materials is crucial. In this study, we successfully synthesized nitrogen-doped Co6Mo6C supported on nitrogen-doped graphene (N-Co6Mo6C/NC). The catalyst exhibited high performance and durability in alkaline electrolytes (1.0 M KOH) for hydrogen evolution, showcasing an overpotential of 185 mV at a current density of 100 mA cm-2 and a Tafel slope of 80 mV dec-1. These findings present a novel avenue for the fabrication of efficient bimetallic carbide catalysts.
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The photosensitive unit and conjugation play a significant role in photocatalytic performance of covalent organic frameworks (COFs). In this work, a series of COFs that introduced the phenyl phenanthridine as photosensitive unit with different planarity of linkages were synthesized and the common regulation between them for photocatalysis hydrogen evolution reaction (HER) was also studied. The results indicate that DHTB-PPD, with 2/3 planarity linkages (ß-ketoenamine/imine is 2/3) and the phenyl phenanthridine as building blocks, shows the narrowest bandgap and the strongest charge separation efficiency. Therefore, it shows the highest H2 production rate of 12.13 mmol g-1 h-1. The optimal photocatalytic efficiency of DTHB-PPD can be attributed to the combined effect of the photosensitive unit and the long-range ordering of the COF skeleton. According to The Density Functional Theory (DFT), the O site on ß-ketoamine is the most possible H2 generation site, but the photocatalytic efficiency of TP-PPD, with the highest skeletal conjugation and the highest proportion of ß-ketoamine is not the most efficient photocatalyst, indicating that the long-range ordering of COFs is important on photocatalytic performance. Thus, these findings provide valuable guidance for the structural design of COFs photocatalysts.
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Topological defects are inevitable existence in carbon-based frameworks, but their intrinsic electrocatalytic activity and mechanism remain under-explored. Herein, the hydrogen evolution reaction (HER) of pentagonal carbon-rings is probed by constructing pentagonal ring-rich carbon (PRC), with optimized electronic structures and higher HER activity relative to common hexagonal carbon (HC). Furthermore, to improve the reactivity, we couple Ru clusters with PRC (Ru@PRC) through p-d orbital hybridization between C and Ru atoms, which drives a shortcut transfer of electrons from Ru clusters to pentagonal rings. The electron-deficient Ru species leads to a notable negative shift in d-band centers of Ru and weakens their binding strength with hydrogen intermediates, thus enhancing the HER activity in different pH media. Especially, at a current density of 10 mA cm-2, PRC greatly reduces alkaline HER overpotentials from 540 to 380 mV. And Ru@PRC even exhibits low overpotentials of 28 and 275 mV to reach current densities of 10 and 1000 mA cm-2, respectively. Impressively, the mass activity and price activity of Ru@PRC are 7.83 and 15.7 times higher than that of Pt/C at the overpotential of 50 mV. Our data unveil the positive HER reactivity of pentagonal defects and good application prospects.
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The production of hydrogen gas as an environmentally friendly and emission-free fuel source, has emerged as the preeminent substitute for traditional fossil fuels. The demand for a viable and low-cost substitute of the anodic Oxygen Evolution Reaction (OER) in hydrogen gas production has led researchers to explore the Hydrazine Oxidation Reaction (HzOR), aiming to reduce overpotential. In this study, we present the synthesis of a NiSeP@NiCo/Cu electrocatalyst via electrodeposition method, offering precise control over parameter adjustments and an affordable price. The binder-free nanosheet structure of this electrocatalyst demonstrates improved performance in water electrolysis, resulting in potentials of -40 and -134 mV vs. Reversible Hydrogen Electrode (RHE) for Hydrogen Evolution Reaction (HER) and 0.041 and 0.194 V (vs. RHE) for HzOR (i = 10 and 100 mA.cm-2). The electrode has excellent features, including active electrochemical surface, synergistic effects among the elements, high stability, super-hydrophilicity and super-aerophobicity. The Bi-functional performance of electrode was tested in a two-electrode set for HER/HzOR, the cell voltage required to reach current densities of 10 and 100 mA.cm-2 were determined as 0.071 and 0.298 V respectively. On the whole, this work presents the excellent capabilities of the synthesized electrode (NiSeP@NiCo/Cu) for hydrogen gas production.
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High-entropy alloys (HEAs) present both significant potential and challenges for developing efficient electrocatalysts due to their diverse combinations and compositions. Here, we propose a procedural approach that combines high-throughput experimentation with data-driven strategies to accelerate the discovery of efficient HEA electrocatalysts for the hydrogen evolution reaction (HER). This enables the rapid preparation of HEA arrays with various element combinations and composition ratios within a model system. The intrinsic activity of the HEA arrays is swiftly screened using scanning electrochemical cell microscopy (SECCM), providing precise composition-activity data sets for the HEA system. An ensemble machine learning (EML) model is then used to predict the activity database for the composition subspace of the system. Based on these database results, two groups of promising catalysts are recommended and validated through actual electrocatalytic evaluations. This procedural approach, which combines high-throughput experimentation with data-driven strategies, provides a new pathway to accelerate the discovery of efficient HEA electrocatalysts.
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Heteroatom immobilization engineering (HAIE) is becoming a forefront approach in materials science and engineering, focusing on the precise control and manipulation of atomic-level interactions within heterogeneous systems. HAIE has emerged as an efficient strategy to fabricate single-atom sites for enhancing the performance of metal-based batteries. Despite the significant progress achieved through HAIE in metal anodes for metal-based batteries, several critical challenges such as metal dendrites, side reactions, and sluggish reaction kinetics are still present. In this review, we delve into the fundamental principles underlying heteroatom immobilization engineering in metal anodes, aiming to elucidate its role in enhancing the electrochemical performance in batteries. We systematically investigate how HAIE facilitates uniform nucleation of metal in anodes, how HAIE inhibits side reactions at the metal anode-electrolyte interface, and the role of HAIE in promoting the desolvation of metal ions and accelerating reaction kinetics within metal-based batteries. Finally, we discuss various strategies for implementing HAIE in electrode materials, such as high-temperature pyrolysis, vacancy reduction, and molten-salt etching and anchoring. These strategies include selecting appropriate heteroatoms, optimizing immobilization methods, and constructing material architectures. They can be utilized to further refine the performance to enhance the capabilities of HAIE and facilitate its widespread application in next-generation metal-based battery technologies.
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We propose a new class of H2 evolution photocatalyst containing TMD not as a co-catalyst, but as a photosensitizer: MoSe2/C60-dendron nanohybrids, assisted by 1-benzyl-1,4-dihydronicotinamide (BNAH) as a sacrificial donor and Pt nanoparticles as co-catalysts. The 2D/0D mixed-dimensional heterojunction formed by MoSe2 and C60 is highly effective in generating mobile carriers under visible and NIR light irradiation. This process involves electron extraction from the exciton in MoSe2 to C60, followed by electron transfer to Pt nanoparticles via MV2+, leading to H2 production from water. Even NIR light, such as 800 nm light corresponding to the A-exciton absorption of MoSe2, can facilitate water splitting. The EQY of the H2 evolution reaction was estimated to be 0.0027%.
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The photocatalytic hydrogen production performance of semiconductor materials can be improved by co-catalyst modification. In most of the studies, the size of the co-catalyst is relatively small compared to the primary catalyst. However, in this study, we employed a novel strategy by synthesizing a relatively large-sized Cu2MoS4 as the co-catalyst and in situ loading smaller-sized Zn0.5Cd0.5S onto Cu2MoS4, verifying that Cu2MoS4 enhances the photocatalytic hydrogen production efficiency of Zn0.5Cd0.5S. It can be observed by scanning electron microscopy (SEM) that the lateral size of 2D Cu2MoS4 is at least 50 times larger than the Zn0.5Cd0.5S nanoparticle particle size. In addition, Density Functional Theory (DFT) calculations have demonstrated that the active site for hydrogen production in the composite is located in Cu2MoS4. The large-sized of Cu2MoS4 not only provides more active sites but also broadens the electron transport channel, which is conducive to promoting the transfer of photogenerated electrons from Zn0.5Cd0.5S. This work enriches the study of large-sized materials as co-catalyst and provides a strategy for the construction of composite catalysts.
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The layered double hydroxides (LDHs) have demonstrated significant potential as non-noble-metal electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Their unique compositional and structural properties contribute to their efficiency and stability as catalysts. In this study, CoCuFe-LDH composites were grown on graphene (G) via a cost-effective and straightforward one-step hydrothermal process. A 2-level full-factorial model was employed to determine the impact of Co (1.5, 3, and 4.5 mmol) and graphene (10, 30, and 50 mg) concentrations on the onset potential of OER and HER, which were the chosen response variables. OER and HER activity variabilities were assessed in triplicate using Co[3]Cu[3]Fe[3]-LDH/G[30] (central point), which were determined at 0.01% and 0.02%, respectively. Statistical analyses demonstrated that Co[4.5]Cu[3]Fe[3]-LDH/G[10] and Co[1.5]Cu[3]Fe[3]-LDH/G[10] showed the lowest onset potential at 1.52 V and -0.32 V (V vs RHE) for the OER and HER, respectively, suggesting that a high cobalt concentration enhances OER performance, while optimal HER catalysis was achieved with lower cobalt concentrations. Moreover, the trimetallic composites exhibited good stability with negligible loss of catalytic activity over 24 h.