Abstract
Engineering catalytic sites at the atomic level provides an opportunity to understand the catalyst’s active sites, which is vital to the development of improved catalysts. Here we show a ...reliable and tunable polyoxometalate template-based synthetic strategy to atomically engineer metal doping sites onto metallic 1T-MoS
2
, using Anderson-type polyoxometalates as precursors. Benefiting from engineering nickel and oxygen atoms, the optimized electrocatalyst shows great enhancement in the hydrogen evolution reaction with a positive onset potential of ~ 0 V and a low overpotential of −46 mV in alkaline electrolyte, comparable to platinum-based catalysts. First-principles calculations reveal co-doping nickel and oxygen into 1T-MoS
2
assists the process of water dissociation and hydrogen generation from their intermediate states. This research will expand on the ability to improve the activities of various catalysts by precisely engineering atomic activation sites to achieve significant electronic modulations and improve atomic utilization efficiencies.
Iron–nickel sulfide ((Ni,Fe)3S2) is one of the most promising bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media ...because of their metallic conductivity and low cost. However, the reported HER activity of (Ni,Fe)3S2 is still unsatisfactory. Herein, three-dimensional self-supported phosphorus-doped (Ni,Fe)3S2 nanosheet arrays on Ni foam (P-(Ni,Fe)3S2/NF) are synthesized by a simple one-step simultaneous phosphorization and sulfuration route, which exhibits dramatically enhanced HER activity as well as drives remarkable OER activity. The incorporation of P significantly optimized the hydrogen/water absorption free energy (ΔG H*/ΔG H2O*), enhanced electrical conductivity, and increased electrochemical surface area. Accordingly, the optimal P-(Ni,Fe)3S2/NF exhibits relatively low overpotentials of 98 and 196 mV at 10 mA cm–2 for HER and OER in 1 M KOH, respectively. Furthermore, an alkaline electrolyzer comprising the P-(Ni,Fe)3S2/NF electrodes needs a very low cell voltage of 1.54 V at 10 mA cm–2 and exhibits long-term stability and outperforms most other state-of-the-art electrocatalysts. The reported electrocatalyst activation approach by anion doping can be adapted for other transition-metal chalcogenides for water electrolysis, offering great promise for future applications.
Engineering the surface structure at the atomic level can be used to precisely and effectively manipulate the reactivity and durability of catalysts. Here we report tuning of the atomic structure of ...one-dimensional single-crystal cobalt (II) oxide (CoO) nanorods by creating oxygen vacancies on pyramidal nanofacets. These CoO nanorods exhibit superior catalytic activity and durability towards oxygen reduction/evolution reactions. The combined experimental studies, microscopic and spectroscopic characterization, and density functional theory calculations reveal that the origins of the electrochemical activity of single-crystal CoO nanorods are in the oxygen vacancies that can be readily created on the oxygen-terminated {111} nanofacets, which favourably affect the electronic structure of CoO, assuring a rapid charge transfer and optimal adsorption energies for intermediates of oxygen reduction/evolution reactions. These results show that the surface atomic structure engineering is important for the fabrication of efficient and durable electrocatalysts.
Perovskite nanocrystals (NCs) have attracted attention due to their high photoluminescence quantum yield (PLQY) in solution; however, maintaining high emission efficiency in the solid state remains a ...challenge. This study presents a solution‐phase synthesis of efficient green‐emitting perovskite NCs (CsPbBr3) embedded in robust and air‐stable rhombic prism hexabromide (Cs4PbBr6) microcrystals, reaching a PLQY of 90%. Theoretical modeling and experimental characterization suggest that lattice matching between the NCs and the matrix contribute to improved passivation, while spatial confinement enhances the radiative rate of the NCs. In addition, dispersing the NCs in a matrix prevents agglomeration, which explains their high PLQY.
Solution‐phase synthesis of efficient green‐emitting perovskite nanocrystal (NC) inclusions in rhombic prism microcrystals is presented. A theoretical model is built on the basis of experimental characterization of the material and further justified by means of density functional theory simulations. The potential of lattice‐matching between the NCs and the matrix strongly improves the interface, leading to high performance metrics in the solid‐state.
Converting CO2 and H2O into carbon‐based fuel by IR light is a tough task. Herein, compared with other single‐component photocatalysts, the most efficient IR‐light‐driven CO2 reduction is achieved by ...an element‐doped ultrathin metallic photocatalyst‐Ni‐doped CoS2 nanosheets (Ni‐CoS2). The evolution rate of CH4 over Ni‐CoS2 is up to 101.8 μmol g−1 h−1. The metallic and ultrathin nature endow Ni‐CoS2 with excellent IR light absorption ability. The PL spectra and Arrhenius plots indicate that Ni atoms could facilitate the separation of photogenerated carriers and the decrease of the activation energy. Moreover, in situ FTIR, DFT calculations, and CH4‐TPD reveal that the doped Ni atoms in CoS2 could effectively depress the formation energy of the *COOH, *CHO and desorption energy of CH4. This work manifests that element doping in atomic level is a powerful way to control the reaction intermediates, providing possibilities to realize high‐efficiency IR‐light‐driven CO2 reduction.
It is a tough task to achieve IR‐light‐driven CO2 reduction. Herein, an element‐doped ultrathin metallic photocatalyst is designed to achieve IR‐light‐driven CO2 reduction. Among the reported single‐component photocatalysts, the most efficient IR‐light‐driven CO2 reduction is realized by Ni‐doped CoS2 nanosheets.
To date, effective control over the electrochemical reduction of CO2 to multicarbon products (C ≥ 2) has been very challenging. Here, we report a design principle for the creation of a selective yet ...robust catalytic interface for heterogeneous electrocatalysts in the reduction of CO2 to C2 oxygenates, demonstrated by rational tuning of an assembly of nitrogen-doped nanodiamonds and copper nanoparticles. The catalyst exhibits a Faradaic efficiency of ~63% towards C2 oxygenates at applied potentials of only −0.5 V versus reversible hydrogen electrode. Moreover, this catalyst shows an unprecedented persistent catalytic performance up to 120 h, with steady current and only 19% activity decay. Density functional theory calculations show that CO binding is strengthened at the copper/nanodiamond interface, suppressing CO desorption and promoting C2 production by lowering the apparent barrier for CO dimerization. The inherent compositional and electronic tunability of the catalyst assembly offers an unrivalled degree of control over the catalytic interface, and thereby the reaction energetics and kinetics.The interfacing of Cu with nitrogen-doped nanodiamond enables the electrocatalytic production of C2 oxygenates from CO2 with promising stability.
Earth-abundant first-row (3d) transition metal–based catalysts have been developed for the oxygen-evolution reaction (OER); however, they operate at overpotentials substantially above thermodynamic ...requirements. Density functional theory suggested that non-3d high-valency metals such as tungsten can modulate 3d metal oxides, providing near-optimal adsorption energies for OER intermediates. We developed a room-temperature synthesis to produce gelled oxyhydroxides materials with an atomically homogeneous metal distribution. These gelled FeCoW oxyhydroxides exhibit the lowest overpotential (191 millivolts) reported at 10 milliamperes per square centimeter in alkaline electrolyte. The catalyst shows no evidence of degradation after more than 500 hours of operation. X-ray absorption and computational studies reveal a synergistic interplay between tungsten, iron, and cobalt in producing a favorable local coordination environment and electronic structure that enhance the energetics for OER.
Electrochemical reduction of carbon dioxide (CO^sub 2^) to carbon monoxide (CO) is the first step in the synthesis of more complex carbon-based fuels and feedstocks using renewable electricity1-7. ...Unfortunately, the reaction suffers from slow kinetics7,8 owing to the low local concentration of CO^sub 2^ surrounding typical CO^sub 2^ reduction reaction catalysts. Alkali metal cations are known to overcome this limitation through non-covalent interactions with adsorbed reagent species9,10, but the effect is restricted by the solubility of relevant salts. Large applied electrode potentials can also enhance CO^sub 2^ adsorption11, but this comes at the cost of increased hydrogen (H^sub 2^) evolution. Here we report that nanostructured electrodes produce, at low applied overpotentials, local high electric fields that concentrate electrolyte cations, which in turn leads to a high local concentration of CO^sub 2^ close to the active CO^sub 2^ reduction reaction surface. Simulations reveal tenfold higher electric fields associated with metallic nanometre-sized tips compared to quasi-planar electrode regions, and measurements using gold nanoneedles confirm a field-induced reagent concentration that enables the CO^sub 2^ reduction reaction to proceed with a geometric current density for CO of 22 milliamperes per square centimetre at -0.35 volts (overpotential of 0.24 volts). This performance surpasses by an order of magnitude the performance of the best gold nanorods, nanoparticles and oxidederived noble metal catalysts. Similarly designed palladium nanoneedle electrocatalysts produce formate with a Faradaic efficiency of more than 90 per cent and an unprecedented geometric current density for formate of 10 milliamperes per square centimetre at -0.2 volts, demonstrating the wider applicability of the field-induced reagent concentration concept.
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