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[Display omitted] • B-N doped biphenylene are electronically and dynamically stable with metallic or semiconducting characteristics. • Uniaxial lattice strain engineering is an effective approach to activating inert BPN and BCN-BPNs toward HER. • The best overpotential for HER is achieved to be 0.011 V by finely tuned strain. • HER activities were determined not only by the active sites but also by the surrounding microenvironment. The exploration of novel metal-free electrocatalysts with excellent activity and stability is important for scaling up hydrogen production via water splitting. Herein, we report a series of novel two-dimensional networks obtained by doping biphenylene (BPN) with B-N pairs, referred to as BCN-BPNs. Density functional theory calculations indicate that the designed BCN-BPNs are electronically and dynamically stable with metallic or semiconducting characteristics. It is further revealed that uniaxial lattice strain engineering is an effective approach to activating inert BPN and BCN-BPNs toward the hydrogen evolution reaction (HER). The best overpotential for HER is predicted to be 0.011 V, achieved by finely tuning strain. A machine learning model with an extreme gradient boosting regressor and a polynomial feature approach was successfully built to predict HER activities. The model achieved mean absolute errors and root mean squared errors of 0.068 and 0.261, respectively. Feature importance analysis highlights the role of both active sites and their microenvironment in determining HER activities. Our study suggests a series of novel metal-free BCN-BPNs with considerable potential for HER. Additionally, a predictive strategy is proposed for fast screening, which would benefit the development of HER catalysts that exhibit both cost-effectiveness and superior performance. [ABSTRACT FROM AUTHOR]

• Boron based molecules as electrolyte additives is more efficient in binding PF 6 - ion. • Boron based podand additives promote the diffusion of Li+ and lowering viscosity under various conditions. • Our designed TMF is more effective additive than the common additive, TPF, considering solvation properties of Li+ ions. • TMF performed under a wide range of temperatures and external electric fields. This article explores the potential of boron based molecules as electrolyte additives in lithium ion batteries (LIBs) to increase conductivity and solid electrolyte interface formation. Specifically, a new class of B-based podand molecule is introduced as an anion receptor additive in LIB electrolytes. The efficacy of this novel additive is studied using Density functional theory (DFT) and atomistic molecular dynamics (MD) simulation, and its performance is compared to a commonly used B-based additive, TPF, in different solvent environments. Results show that the designed additive is more efficient in binding PF 6 - ion, promoting the diffusion of Li+ and lowering viscosity under various conditions. Some calculated properties are validated with existing experimental data. This research holds promise for the development of more efficient and effective energy storage solutions. [ABSTRACT FROM AUTHOR]

The effect of the amount of Hartree-Fock mixing parameter ( α) and of the screening parameter ( w) defining the range separated HSE type hybrid functional is systematically studied for a series of seven metal oxides: TiO2, ZrO2, CuO2, ZnO, MgO, SnO2, and SrTiO3. First, reliable band gap values were determined by comparing the optimal α reproducing the experiment with the inverse of the experimental dielectric constant. Then, the effect of the w in the HSE functional on the calculated band gap was explored in detail. Results evidence the existence of a virtually infinite number of combinations of the two parameters which are able to reproduce the experimental band gap, without a unique pair able to describe the full studied set of materials. Nevertheless, the results point out the possibility of describing the electronic structure of these materials through a functional including a screened HF exchange and an appropriate correlation contribution. © 2017 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

[Display omitted] Transition-metal-atom anchored graphdiynes (TM@GDY, TM = Mn, Fe, Co, Ni and Cu) have already been synthesized and found applications in hydrogen evolution, nitrogen fixation and etc. By means of first-principle predictions and test experiments, we propose here that Fe@GDY and Co@GDY are efficient catalysts for the sustainable conversion of O 3 to O 2. These two catalysts can spontaneously chemisorb O 3 with zero reaction barrier and have low O 3 conversion barriers (0.31 eV and 0.19 eV, respectively). The O 3 decomposition experiment in a continuous flow membrane reactor and electron paramagnetic resonance results verify that Fe@GDY and Co@GDY are efficient catalysts under humid conditions. Raman spectra prove the formation of the key Fe-O/Co-O and Fe O O and Co O O intermediates. The hydrophobic nature of graphdiyne and the strongest chemisorption of O 3 among tested ambient gases, make Fe@GDY and Co@GDY ideal catalysts under both dry and humid conditions. These findings would stimulate future explorations on metal anchored GDY-based catalysts for applications of toxic gas decomposition or fixation. [ABSTRACT FROM AUTHOR]

Ti, Cr, Zr and Hf embedded novel C 6 N 3 containing sp-N exhibit excellent performance toward hydrogen evolution. [Display omitted] Two-dimensional (2D) carbon nitrides (C x N y) have great potential in advanced fields such as energy harvest and storage. We report a novel 2D C x N y , C 6 N 3 , comprising sp-N and sp2-C atoms. Density functional theory calculations indicate that electronically, thermally, and dynamically stable C 6 N 3 is metallic even when cut into very narrow nanoribbons. C 6 N 3 adsorbed single atoms of 3d, 4d, and 5d transition metals to fabricate single-atom catalysts (SACs) for an electrocatalytic hydrogen evolution reaction (HER). Among all SACs studied, Ti-, Cr-, Zr-, and Hf-embedded C 6 N 3 had excellent overall performance including promising stability, moderate binding strength of H and H 2 , and good electrical conductivity. Our results suggest a novel C 6 N 3 with an sp-N skeleton that has great potential for HER. More investigations are needed to further understand the properties and applications of C 6 N 3 in other fields. [ABSTRACT FROM AUTHOR]

[Display omitted] • β-graphyne/graphdiyne nanoribbons are excellent bifunctional CMFCs for the ORR and HER after functionalization by manipulating the edge shape or N-doping. • Δ E H* is a universal descriptor for predicting the bifunctional activities of GYFs. • Extreme gradient boosting algorithm can predict the bifunctional activities of GYFs. • This study can accelerate the search for highly active GYFs for the ORR and HER. Recently, graphyne and its family members (GYFs) have emerged as promising carbon-based metal-free catalysts (CMFCs) for the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). Herein, we performed density functional theory simulations to explore the ORR and HER performances of β-graphyne/graphdiyne nanoribbons (βGyNRs/βGDyNRs), which have received scant attention. Our results reveal that βGyNRs/βGDyNRs are excellent bifunctional CMFCs after functionalization by manipulating the edge shape or N-doping. Moreover, we verified the role of the binding strength of the H atom (Δ E H*) as a universal descriptor for predicting the bifunctional activities for the ORR and HER on GYFs. We also proposed a machine learning model based on an extreme gradient boosting algorithm for predicting the bifunctional activities of GYFs. Feature importance analysis indicated that the atomic charge of the catalytic site (Q) played a determining role in the ORR activity of the GYFs. This study not only identifies promising GYFs, but also accelerates the search for highly active GYFs for the ORR and HER. [ABSTRACT FROM AUTHOR]

Compared to MoS 2 and Fe 2 O 3 , MOF-derived Fe 2 O 3 @MoS 2 possesses the most encouraging electrochemical ammonia synthesis activity with a high NH 3 yield of 112.15 μg h−1 mg cat. -1 at −0.6 V vs RHE, and a prominent FE of 8.62% at −0.4 V vs RHE. [Display omitted] • Fe 2 O 3 nanoparticles anchored on MoS 2 nanoflowers are efficient EAS electrocatalyst with NH 3 yield of 112.15 μg h−1 mg cat −1. • Fe 2 O 3 @MoS 2 is more active than that of MoS 2 owing to its double active sites of Fe and Mo. • The fifth hydrogenation process is the potential-determining step. Electrochemical ammonia synthesis (EAS) is considered to be an ecofriendly and sustainable method for artificial N 2 fixation. It is urgent to develop cost-effective and efficient electrocatalysts for EAS because present catalysts have low activity and poor selectivity. Herein, Fe 2 O 3 nanoparticles anchored on MoS 2 nanoflowers (Fe 2 O 3 @MoS 2) were developed as a highly efficient EAS electrocatalyst under ambient conditions. Electrochemical measurements indicate that Fe 2 O 3 @MoS 2 achieves a remarkable NH 3 yield of 112.15 μg h−1 mg cat −1 at − 0.6 V vs. reversible hydrogen electrode (RHE) and a high faradaic efficiency (FE) of 8.62% at − 0.4 V vs. RHE in 0.1 M Na 2 SO 4 , much better than the EAS performance of separate MoS 2 and Fe 2 O 3. The superior electrochemical stability is confirmed by long-term (at least 24 h) continuous tests. Density functional theory (DFT) calculations show that Fe 2 O 3 @MoS 2 , compared to MoS 2 , is better able to activate inert N 2 molecules, as reflected by its greater adsorption energy (−0.32 eV vs. − 0.10 eV), greater N≡N bond distance (1.223 Å vs. 1.159 Å), lower energy barrier (0.40 eV vs. 0.78 eV), and greater charge transfer from active sites to N 2 molecules (1.16 e − vs. 0.62 e −). Thus, this work provides new perspectives on the development of efficient EAS catalysts using MoS 2 -based materials as the substrate. [ABSTRACT FROM AUTHOR]

Double B-doping make graphyne achieve ultrahigh NRR activity. [Display omitted] • Graphyne materials with boron doping showed enhanced catalytic activity for nitrogen reduction reaction. • Double boron doping could be efficient metal free catalysts for N 2 fixation and NH 3 synthesis. • We propose a new energy-related descriptor showing a good volcano-shaped relationship to the limiting potential. The electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions is an emerging technique to address energy shortages and climate change. Thus, developing efficient but low-cost electrocatalysts is important. In the present paper, we applied γ-graphyne (γGy) doped with B, N, O, P and S as NRR catalysts, and the activities of these catalysts were studied by extensive density functional theory (DFT) calculations. Our results suggest that single N, O, P and S doping are not effective in enhancing γGy NRR activity, and the γGy with B(sp2)-C(sp)-B(sp) configuration has excellent overall NRR activity with a record low limiting potential (−0.12 V), good conductivity, low hydrogen evolution reaction activity and high dynamic stability. We revealed that the sp-C directly connected to active sp-B can be an energy buffer that makes a flat potential energy surface. Overall, our research provides several good NRR catalysts by carefully controlling the doping sites and provides a new strategy for further development of metal-free catalysts for the NRR. [ABSTRACT FROM AUTHOR]