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W single atom doped graphitic carbon nitride porous unltrathin nanosheets (WSA-CN-PUNS) catalyst has been successfully fabricated by using the polyprrole-polyoxometalate/g-C3N4 ...composites as precursor, in combination with a thermal oxidation etching process. The as-prepared W-doped sample shows remarkably enhanced photocatalytic H2 production performance. Meanwhile, as the bifunctional photocatalyst for H2 evolution and benzyl alcohol selective oxidation, it can still display extraordinary activity.
•The W single atom doped g-C3N4 porous unltrathin nanosheets can be synthesized.•The W doping can adjust the electronic structure and inhibit the carrier recombination.•The WSA-CN-PUNS shows 9.7 times higher H2 production rate under visible light.•The WSA-CN-PUNS can be used as a dual-function photocatalyst.
In this work, we report a W single atoms modified g-C3N4 porous unltrathin nanosheets (WSA-CN-PUNS) catalyst for photocatalytic H2 evolution, which is synthesized by simply calcining the polyprrole-polyoxometalate/g-C3N4 composite in air. DFT calculation and experimental results reveal that the WSA-CN-PUNS catalyst has a reduced band-gap, dopant-related defect levels and inhibited charge recombination. As a result, the WSA-CN-PUNS shows an activity of 3.02 mmol h−1 g−1 toward H2 production under visible light, which is 9.7 times higher than that of pristine g-C3N4. Meanwhile, for eliminating the waste of sacrifice agent, we demonstrate an alternative approach by coupling the photocatalytic H2 evolution with benzyl alcohol oxidation, and the H2/benzaldehyde production rates are 298.7/305.1 μmol h−1 g−1, respectively. This work not only provides a new strategy for designing high-efficiency single W atom dispersed hybrid catalyst, but also demonstrates the great potential of its practical applications in photocatalytic H2 evolution.
Electrochemical water splitting for H2 production is limited by the sluggish anode oxygen evolution reaction (OER), thus using hydrazine oxidation reaction (HzOR) to replace OER has received great ...attention. Here we report the hierarchical porous nanosheet arrays with abundant Ni3N‐Co3N heterointerfaces on Ni foam with superior hydrogen evolution reaction (HER) and HzOR activity, realizing working potentials of −43 and −88 mV for 10 mA cm−2, respectively, and achieving an industry‐level 1000 mA cm−2 at 200 mV for HzOR. The two‐electrode overall hydrazine splitting (OHzS) electrolyzer requires the cell voltages of 0.071 and 0.76 V for 10 and 400 mA cm−2, respectively. The H2 production powered by a direct hydrazine fuel cell (DHzFC) and a commercial solar cell are investigated to inspire future practical applications. DFT calculations decipher that heterointerfaces simultaneously optimize the hydrogen adsorption free energy (ΔGH*) and promote the hydrazine dehydrogenation kinetics. This work provides a rationale for advanced bifunctional electrocatalysts, and propels the practical energy‐saving H2 generation techniques.
An efficient bifunctional electrocatalyst toward hydrazine‐assisted H2 production was designed by constructing the Ni3N‐Co3N heterointerfaces on Ni foam (Ni3N‐Co3N PNAs/NF). The catalyst can achieve energy‐saving hydrogen production in an overall hydrazine splitting (OHzS) unit, showing its potential for practical applications.
Partially exposed RuP
2
on carbon endows outstanding activity to hydrazine oxidation and hydrogen evolution catalysis.
Replacing the sluggish anode reaction in water electrolysis with ...thermodynamically favorable hydrazine oxidation could achieve energy-efficient H
2
production, while the shortage of bifunctional catalysts limits its scale development. Here, we presented the scalable one-pot synthesis of partially exposed RuP
2
nanoparticle–decorated carbon porous microsheets, which can act as the superior bifunctional catalyst outperforming Pt/C for both hydrazine oxidation reaction and hydrogen evolution reaction, where an ultralow working potential of −70 mV and an ultrasmall overpotential of 24 mV for 10 mA cm
−2
can be achieved. The two-electrode electrolyzer can reach 10 mA cm
−2
with a record-low cell voltage of 23 mV and an ultrahigh current density of 522 mA cm
−2
at 1.0 V. The DFT calculations unravel the notability of partial exposure in the hybrid structure, as the exposed Ru atoms are the active sites for hydrazine dehydrogenation, while the C atoms exhibit a more thermoneutral value for H* adsorption.
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•The NiCo-MoNi4 HMNAs/NF obtained by integrating NiCo and MoNi4 on MoOx substrate.•The NiCo-MoNi4 HMNAs/NF shows high electrocatalytic activity for HER and HzOR.•The overall hydrazine ...splitting delivers a promising current density of 250 mA cm−2 at 0.63 V.
Using hydrazine oxidation reaction (HzOR) to replace sluggish oxygen evolution could be an effective strategy to realize energy-saving hydrogen production, while the development of efficient bifunctional electrocatalysts still remains a significant challenge. Herein, we report a hierarchical multi-component nanosheet arrays grown on Ni foam composed of abundant NiCo/MoNi4 heterostructure interfaces on the amorphous MoOx substrate (denoted as NiCo-MoNi4 HMNAs/NF), which can simultaneously achieve the current density of 10 mA cm−2 at a low working potential of −30 mV (vs. RHE) for HzOR and a small overpotential of 68 mV for HER. Importantly, the post-catalysis characterizations further disclose that the partial formation of transition metal hydroxide species probably endow favorable absorption for hydroxyl intermediates, leading to the high performance and durability. Moreover, a two-electrode system based on NiCo-MoNi4 HMNAs/NF can reach the current density of 250 mA cm−2 with a cell voltage of 0.63 V for overall hydrazine splitting (OHzS) system.
An advanced integrated electrode for high-performance supercapacitors has been designed by growing hierarchical NiCo(2)O(4)@MnO(2) core-shell heterostructured nanowire arrays on nickel foam. Such ...unique array nanoarchitectures exhibit remarkable electrochemical performance with high capacitance and desirable cycle life at high rates.
Polymer‐based dielectric materials play a key role in advanced electronic devices and electric power systems. Although extensive research has been devoted to improve their energy‐storage ...performances, it is a great challenge to increase the breakdown strength of polymer nanocomposites in terms of achieving high energy density and good reliability under high voltages. Here, a general strategy is proposed to significantly improve their breakdown strength and energy storage by adding negatively charged Ca2Nb3O10 nanosheets. A dramatically enhanced breakdown strength (792 MV m−1) and the highest energy density (36.2 J cm−3) among all flexible polymer‐based dielectrics are observed in poly(vinylidene fluoride)‐based nanocomposite capacitors. The strategy generalizability is verified by the similar substantial enhancements of breakdown strength and energy density in polystyrene‐based nanocomposites. Phase‐field simulations demonstrate that the further enhanced breakdown strength is ascribed to the local electric field, produced by the negatively charged Ca2Nb3O10 nanosheets sandwiched with the positively charged polyethyleneimine, which suppresses the secondary impact‐ionized electrons and blocks the breakdown path in nanocomposites. The results demonstrate a new horizon of high‐energy‐density flexible capacitors.
A general strategy is developed to enhance energy storage of nanocomposites. Through inserting negatively charged Ca2Nb3O10 nanosheets into a polymer matrix, a reversed local electric field is generated and further blocks the breakdown path. A record‐high energy storage of 36.2 J cm−3 is achieved in poly(vinylidene fluoride). The strategy is also utilized in polystyrene‐based nanocomposites and is verified by phase‐field simulations.
As promising hydrogen energy carrier, formic acid (HCOOH) plays an indispensable role in building a complete industry chain of a hydrogen economy. Currently, the biomass upgrading assisted water ...electrolysis has emerged as an attractive alternative for co‐producing green HCOOH and H2 in a cost‐effective manner, yet simultaneously affording high current density and Faradaic efficiency (FE) still remains a big challenge. Here, the ternary NiVRu‐layered double hydroxides (LDHs) nanosheet arrays for selective glycerol oxidation and hydrogen evolution catalysis are reported, which yield an industry‐level 1 A cm−2 at voltage of 1.933 V, meanwhile showing considerable HCOOH and H2 productivities of 12.5 and 17.9 mmol cm−2 h−1, with FEs of almost 80% and 96%, respectively. Experimental and theoretical results reveal that the introduced Ru atoms can tune the local electronic structure of Ni‐based LDHs, which not only optimizes hydrogen adsorption kinetics for HER, but also reduces the reaction energy barriers for both the conversion of NiII into GOR‐active NiIII and carboncarbon (CC) bond cleavage. In short, this work highlights the potential of large‐scale H2 and HCOOH productions from integrated electrocatalytic system and provides new insights for designing advanced electrocatalyst for low‐cost and sustainable energy conversion.
The ternary NiVRu‐LDHs nanosheet arrays are prepared by a one‐step hydrothermal reaction (NiVRu‐LDHs NAs/NF), which realize a green, sustainable, and energy‐saving electrochemical route for formic acid and hydrogen co‐production with high Faradaic efficiencies (almost 80% and 96%) and productivities (12.5 and 17.9 mmol cm−2 h−1) at an industry‐level current density of 1 A cm−2.
For many years, humans have been relentlessly focused on enhancing battery longevity and boosting energy storage capacities. The performance and durability of a battery depend significantly on the ...material used for its electrodes. In this context, merging machine learning with density functional theory (DFT) calculations has emerged as a pivotal approach to advancing the exploration of battery crystal structures. We present a new method that combines a graph convolutional neural network (GNN) with a Transformer convolutional layer, which we call Transformer-GNN. To underscore its efficacy, we benchmarked Transformer-GNN against three established statistical machine learning models: Support Vector Machine, Random Forest, and XGBoost. We also developed a standard GNN, which we refer to as Basic-GNN. Additionally, we compared Basic-GNN with Transformer-GNN to highlight the improvements brought about by incorporating the Transformer convolutional layer. The Transformer-GNN model outperforms the other models, achieving the highest R 2 value of 0.82 and the lowest mean squared error of 0.3161. Our findings demonstrate that the Transformer-GNN can profoundly understand battery crystal structures, thus forging the path toward more sophisticated and durable battery systems. Leveraging the GNN model’s voltage predictions in tandem with the capacity data sourced from the database, we screened and pinpointed Na(NiO2)2 as a high-voltage (higher than 5 V), high-capacity sodium cathode material. We conducted DFT calculations on Na(NiO2)2 and revealed the migration mechanism of the Na ions.
Hierarchical nest-like TiO2-nitrogen-doped-carbon hybrid structures (TiO2/NC-HN) have been synthesized through the supramolecular assembly assisted one-pot strategy, which exhibits impressive ...electrochemical performance for both sodium and potassium ion storage derived from the synergist effect of hierarchical morphology, highly porous structure, strongly coupled interface and the possible oxygen vacancy in TiO2. More importantly, the potassium-ion hybrid capacitors based on TiO2/NC-HN anode could deliver a decent energy density of 108.6 Wh kg−1 and a record cycling life up to 30,000 cycles at the rate of 2.5 A g−1 based on the total mass of anode and cathode.
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•Nest-like TiO2-nitrogen-doped-carbon hybrid structures have been synthesized.•Supramolecular assembly assisted one-pot strategy was employed.•Synergistic effect of hierarchical morphology, porous structure, coupled interface.•KIHCs based on TiO2/NC-HN deliver a decent energy density and a record cycling life.
Energy storage devices beyond lithium, including sodium/potassium ion batteries and hybrid capacities have recently attracted increasing attention due to their particular merit of cost-effectiveness. Currently, there is a common challenging issue in these devices, which is the rapid capacity fading of anodes due to the much larger ionic radius and sluggish kinetics of Na+/K+ intercalation. Herein, we presented the formation of hierarchical nest-like TiO2-nitrogen-doped carbon hybrid nanostructures (denoted as TiO2/NC-HN) through the supramolecular assembly directed one-pot strategy, which exhibits outstanding electrochemical performance for both sodium and potassium ion storage with largely improved specific capacity and cycling stability. Specifically, it can deliver a high specific capacity of 382.5 and 323.1 mAh g−1 at the rate of 100 mA g−1 for Na+ and K+ storage, respectively, and can also maintain ultra-stable cycling capability under high rates. More importantly, the potassium ion hybrid capacitors based on TiO2/NC-HN anode can deliver a high energy/power density of 108.6 Wh kg−1 95 W kg−1 and exhibit superior cycling stability up to 30,000 cycles at the rate of 2.5 A g−1. This work could not only provide a low-cost strategy for advanced hybrid nanostructures, but also benefit the development of energy storage devices based on earth-abundant sodium/potassium.
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