The performances of nonlinear optics (NLO) and thermally activated delayed fluorescence (TADF) materials are strongly related to the torsion angles (θ) between donor (D) and acceptor (A) moieties in ...D–A architecture molecules. However, the underlying relationships connecting θ to the performances of NLO/TADF materials remain unclear. Herein, we present a comprehensive theoretical study on NLO/TADF materials composed of a series of D–A backbone molecules (TPAAP/TPAAQ series and AQ-DMAC/AQ-MeFAC series) to shed light on these relationships. It is found that changing θ via the intramolecular locking strategy can greatly influence values of the first hyperpolarizability (β) and singlet-triplet energy gap (ΔE ST), further leading to better/worse performances of NLO/TADF materials, respectively. Intriguingly, a more detailed analysis indicates that the variation trends between θ and β/ΔE ST are changeable in low θ regions, exhibiting volcano-like relationships. The large coefficients of determination (R 2, ranging from 0.76 to 0.93) suggest that this experimentally measurable parameter (θ) can be used as a promising descriptor to evaluate the performances of related materials. Following the revealed θ–β/θ–ΔE ST correlations, the optimal/worst torsion angles for different materials are identified. These findings highlight the importance of the intrinsic structure–performance relationships, thus providing novel design strategies for high-performance NLO/TADF materials.
Integrating single atoms and clusters into one system is a novel strategy to achieve desired catalytic performances. Compared with homogeneous single-atom cluster catalysts, heterogeneous ones ...combine the merits of different species and therefore show greater potential. However, it is still challenging to construct single-atom cluster systems of heterogeneous species, and the underlying mechanism for activity improvement remains unclear. In this work, we developed a heterogeneous single-atom cluster catalyst (Co n Ir1/N–C) for efficient oxygen evolution. The Ir single atoms worked in synergy with the Co clusters at a distance of about 8 Å, which optimized the configuration of the key intermediates. Consequently, the oxygen evolution activity was significantly improved on Co n Ir1/N–C relative to the Co cluster catalyst (Co n /N–C), exhibiting an overpotential lower by 107 mV than that of Con/N–C at 10 mA cm–2 and a turnover frequency 50.9 times as much as that of Co n /N–C at an overpotential of 300 mV.
The catalytic performance of single-atom catalysts was strictly limited by isolated single-atom sites. Fabricating high-density single atoms to realize the synergetic interaction in neighbouring ...single atoms could optimize the adsorption behaviors of reaction intermediates, which exhibited great potential to break performance limitations and deepen mechanistic understanding of electrocatalysis. However, the catalytic behavior governed by neighbouring single atoms is particularly elusive and has yet to be understood. Herein, we revealed that the synergetic interaction in neighbouring single atoms contributes to superior performance for oxygen evolution relative to isolated Ir single atoms. Neighbouring single atoms was achieved by fabricating high-density single atoms to narrow the distance between single atoms. Electrochemical measurements demonstrated that the Nei-Ir
/CoGaOOH with neighbouring Ir single atoms exhibited a low overpotential of 170 mV at a current density of 10 mA cm
, and long-durable stability over 2000 h for oxygen evolution. Mechanistic studies revealed that neighbouring single atoms synergetic stabilized the *OOH intermediates via extra hydrogen bonding interactions, thus significantly reducing the reaction energy barriers, as compared to isolated Ir single atoms. The discovery of the synergetic interaction in neighbouring single atoms could offer guidance for the development of efficient electrocatalysts, thus accelerating the world's transition to sustainable energy.
Developing efficient and stable catalysts for energy conversion processes such as alkaline oxygen evolution reaction is one of the key measures to solve the energy shortage problems. During alkaline ...oxygen evolution, several electrocatalysts would undergo structural reconstruction from the pre‐catalyst state to the real‐catalyst state. The structural reconstruction may modify the quantity and characterizations of the active sites, thus affecting the configuration and adsorption strength of the reaction key intermediates, which directly influence the activity and stability of the electrocatalysts. Understanding the structural transformation chemistry is essential for the rational design of highly efficient and stable electrocatalysts. In this review, we have deeply discussed the role and regulation strategies of structural reconstruction. Then, on this basis, we described some characterization technologies to probe the structural reconstruction of catalysts during alkaline OER. Finally, we put forward some views on the future research direction of this vital field.
The structural reconstruction of electrocatalysts is strongly correlated with their alkaline OER performance and stability. Understanding structural reconstruction chemistry is crucial for the rational design of electrocatalysts. This review gives an overview of the role, regulating strategies, and characterization technologies of structural reconstruction, which open a door for researchers to design high‐performance electrocatalysts.
Modifying the atomic and electronic structure of platinum-based alloy to enhance its activity and anti-CO poisoning ability is a vital issue in hydrogen oxidation reaction (HOR). However, the role of ...foreign modifier metal and the underlying ligand effect is not fully understood. Here, we propose that the ligand effect of single-atom Cu can dynamically modulate the d-band center of Pt-based alloy for boosting HOR performance. By in situ X-ray absorption spectroscopy, our research has identified that the potential-driven structural rearrangement into high-coordination Cu–Pt/Pd intensifies the ligand effect in Pt–Cu–Pd, leading to enhanced HOR performance. Thereby, modulating the d-band structure leads to near-optimal hydrogen/hydroxyl binding energies and reduced CO adsorption energies for promoting the HOR kinetics and the CO-tolerant capability. Accordingly, PtPdCu1/C exhibits excellent CO tolerance even at 1,000 ppm impurity.
The dominant reaction pathway changes with the composition of the supported PdAu nanoalloys, and the water promotion effect is component-dependent.
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•Maximize the synergistic effect of ...PdAu catalysts on TiO2(101) for CO2 reduction.•CO2 adsorption has a volcanic relationship with activity in “CO2 HYD” pathway.•Activity is related to adsorption energy of CHO and CO in “RWGS + CO HYD” pathway.•The mechanism of water promotion is composition-dependent.
To provide insight into how to realize maximization of the synergistic effect of supported PdAu catalysts, we have performed first-principles calculations for CO2 reduction over PdAu/TiO2(1 0 1). The results indicate that introducing a secondary metal (Au) to supported Pd catalyst and controlling Au concentration can affect the binding energy of reactants and also alter the dominant reaction pathway. The energetically preferred path for CO2 reduction on Pd8-xAux/TiO2 changes from the formate pathway (referred to as the “CO2 HYD” pathway) (x = 0–3) to the reverse water-gas shift and CO hydrogenation (“RWGS + CO HYD”) pathway (x = 4–6). Notably, the CO2 reduction activity shows a volcano trend as a function of the binding energy of the initial reactant CO2* in the “CO2 HYD” pathway or the adsorption energy difference between CHO* and CO* in the “RWGS + CO HYD” pathway. In addition, there is a component-dependent relationship between the water-promotion-effect and the nanoalloy structure. This work proposes fundamental insights into the effect of nanoalloy composition and water promotion in maximizing the synergy of PdAu catalysts for CO2 reduction, providing facile descriptors for the activity of reaction pathways, and offering important guidance for rational design of supported nanoalloy catalysts.
The electrocatalytic activity of transition-metal-based compounds is strongly related to the spin states. However, the underlying relationship connecting spin to catalytic activity remains unclear. ...Herein, we carried out density functional theory calculations on oxygen reduction reaction (ORR) catalyzed by Fe single-atom supported on C
N (C
N-Fe) to shed light on this relationship. It is found that the change of electronic spin moments of Fe and O
due to molecular-catalyst adsorption scales with the amount of electron transfer from Fe to O
, which promotes the catalytic activity of C
N-Fe for driving ORR. The nearly linear relationship between the catalytic activity and spin moment variation suggests electronic spin moment as a promising catalytic descriptor for Fe single-atom based catalysts. Following the revealed relationship, the ORR barrier on C
N-Fe was tuned to be as low as 0.10 eV through judicious manipulation of spin states. These findings thus provide important insights into the relationship between catalytic activity and spin, leading to new strategies for designing transition metal single-atom catalysts.
The remarkable chemical activity of metal single-atom catalysts (SACs) lies in their unique electronic states associated with the low-coordination nature of single-atom sites. Yet, electronic state ...manipulation normally requires direct contact with other atoms, which inevitably changes the low-coordination environment. Herein, we found by first-principle calculations that the activity of a Co SAC for HCOOH dehydrogenation is appreciably enhanced via electronic state manipulation by a noncontact single atom promoter. A Co atom and a Sn/Ge/Pb atom are anchored in the same cavity of a graphitic C2N monolayer. Surprisingly, the nonbonded promoter makes two far splitting spin states of Co almost degenerate via charge redistribution of C2N support. Further, the high-spin Co gives a remarkably low reaction barrier comparable to Pt or Pd catalysts. Our results demonstrate that the activity of a SAC can be tuned via a noncontact promoter, casting new insights into electronic state modulation of SACs on graphene-like support.
As an important factor in the design of catalysts, catalytic descriptor exploration has emerged as a novel frontier in heterogeneous catalysis. Here, the underlying structure–activity relationships ...of Ru-based catalysts are theoretically studied to shed light on this area. Calculations of different competing reaction paths suggest that the HCO*-mediated pathbecause of two synergistic active sitesis more favorable than others. In addition, compared to unadulterated Ru catalysts, the presence of Cl enhances the hydrocarbon production, whereas the presence of S decreases it. After a systematic examination of a series of structure–activity relationships (42 in total), we found that both charge transfer and average charge difference of active Ru atoms are good descriptors for the binding stability of reactants. However, for reactivity the Gibbs free energy of the reactants performs better. More interestingly, due to the quite different catalytic processes of the dissociation and hydrogenation steps, their correlations have opposite slopes.
