Heterostructured Pt-PbS Nanobelt Achieves Remarkable Direct Formic Acid Oxidation Catalysis.

Developing efficient and CO-tolerant platinum (Pt)-based anodic catalysts is challenging for a direct formic acid fuel cell (DFAFC). Herein, we report heterostructured Pt-lead-sulfur (PtPbS)-based nanomaterials with gradual phase regulation as efficient formic acid oxidation reaction (FAOR) catalysts. The optimized Pt-PbS nanobelts (Pt-PbS NBs/C) display the mass and specific activities of 5.90 A mgPt-1 and 21.4 mA cm-2, 2.2/1.2, 1.5/1.1, and 36.9/79.3 times greater than those of PtPb-PbS NBs/C, Pt-PbSO4 NBs/C, and commercial Pt/C, respectively. Simultaneously, it exhibits a higher membrane electrode assembly (MEA) power density (183.5 mW cm-2) than commercial Pt/C (40.3 mW cm-2). This MEA stably operates at 0.4 V for 25 h, demonstrating a competitive potential of device application. The distinctive heterostructure endows the Pt-PbS NBs/C with optimized dehydrogenation steps and resisting the CO poisoning, thus presenting the remarkable FAOR performance. This work paves an effective avenue for creating high-performance anodic catalysts for fuel cells and beyond.

Strain-Triggered Distinct Oxygen Evolution Reaction Pathway in Two-Dimensional Metastable Phase IrO2 via CeO2 Loading.

A strain engineering strategy is crucial for designing a high-performance catalyst. However, how to control the strain in metastable phase two-dimensional (2D) materials is technically challenging due to their nanoscale sizes. Here, we report that cerium dioxide (CeO2) is an ideal loading material for tuning the in-plane strain in 2D metastable 1T-phase IrO2 (1T-IrO2) via an in situ growth method. Surprisingly, 5% CeO2 loaded 1T-IrO2 with 8% compressive strain achieves an overpotential of 194 mV at 10 mA cm-2 in a three-electrode system. It also retained a high current density of 900 mA cm-2 at a cell voltage of 1.8 V for a 400 h stability test in the proton-exchange membrane device. More importantly, the Fourier transform infrared measurements and density functional theory calculation reveal that the CeO2 induced strained 1T-IrO2 directly undergo the *O-*O radical coupling mechanism for O2 generation, totally different from the traditional adsorbate evolution mechanism in pure 1T-IrO2. These findings illustrate the important role of strain engineering in paving up an optimal catalytic pathway in order to achieve robust electrochemical performance.

Motivating Inert Strontium Manganate with Iridium Dopants as Efficient Electrocatalysts for Oxygen Evolution in Acidic Electrolyte.

The search for high-performance and low-cost electrocatalysts in acid conditions still remains a challenging target. Herein, iridium (Ir) doped strontium manganate (named as Irx -SMO) is proposed as an efficient and durable low-iridium electrocatalyst for water oxidation in acidic media. The Ir0.1 -SMO with 75% less iridium in comparison to that of iridium dioxide (IrO2 ) exhibits excellent performance for oxygen evolution reaction (OER), which is even better than most of the iridium-based oxide electrocatalysts. The theoretical outcomes confirm the activation of the inert manganese sites in strontium manganate by the incorporation of iridium dopants. This work reveals the boosted effect of the iridium dopants on the OER activity of strontium manganate, providing a strategy to tune the activity of manganese-based perovskites in electrocatalysis.

Influence factors of CO adsorption on C2N-supported dual-atom catalysts unveiled by machine learning and twofold feature engineering.

Dual-atom catalysts (DACs) have emerged as a compelling frontier in the realm of the electrochemical carbon dioxide reduction reaction (CO2RR). However, elucidating the intrinsic properties of dual-atom pairs and their direct correlation with catalytic activity poses significant challenges. Herein, we investigate CO adsorption on 248 kinds of C2N-supported DACs and analyze the underlying structure-activity relationships of dual transition metal (TM) atoms based on density functional theory (DFT) calculations and machine learning (ML) models. Compared to the direct input of atomic features in the decision tree model of ML, we confirm that extra feature engineering with the introduction of the arithmetic combination of atomic features can better reflect the correlation of dual TM atoms on C2N-based DACs. Further feature importance analysis reveals a strong relationship between the last one occupied orbital radius (rv), group number (G) for dual TM atoms and the CO binding strength, as well as a potential connection with the d band centre (εd). Our work provides deeper insights into the design of DACs and highlights the significance of twofold feature engineering for the synergistic effects between dual TM atoms.

Continuous Phase Regulation of a Pd-Te Hexagonal Nanoplate Library.

Phase regulation of noble metal-based nanomaterials provides a promising strategy for boosting the catalytic performance. However, realizing the continuous phase modulation in two-dimensional structures and unveiling the relevant structure-performance relationship remain significant challenges. In this work, we present the first example of continuous phase modulation in a library of Pd-Te hexagonal nanoplates (HNPs) from cubic-phase Pd4Te, rhombohedral-phase Pd20Te7, rhombohedral-phase Pd8Te3, and hexagonal-phase PdTe to hexagonal-phase PdTe2. Notably, the continuous phase regulation of the well-defined Pd-Te HNPs enables the successful modulation of the distance between adjacent Pd active sites, triggering an exciting way for tuning the relevant catalytic reactions intrinsically. The proof-of-concept oxygen reduction reaction (ORR) experiment shows a Pd-Pd distance-dependent ORR performance, where the hexagonal-phase PdTe HNPs present the best electrochemical performance in ORR (mass activity and specific activity of 1.02 A mg-1Pd and 1.83 mA cm-2Pd at 0.9 V vs RHE). Theoretical investigation reveals that the increased Pd-Pd distance relates to the weak *OH adsorption over Pd-Te HNPs, thus contributing to the remarkable ORR activity of PdTe HNPs. This work advances the phase-controlled synthesis of noble metal-based nanostructures, which gives huge impetus to the design of high-efficiency nanomaterials for diverse applications.

Trace Lattice S Inserted RuO2 Flexible Nanosheets for Efficient and Long-Term Acidic Oxygen Evolution Catalysis.

Pursuing highly active and long-term stable ruthenium (Ru) based oxygen evolution reaction (OER) catalyst for water electrolysis under acidic conditions is of great significance yet a tremendous challenge to date. To solve the problem of serious Ru corrosion in an acid medium, the trace lattice sulfur (S) inserted RuO2 catalyst is prepared. The optimized catalyst (Ru/S NSs-400) has shown a record stability of 600 h for the solely containing Ru (iridium-free) nanomaterials. In the practical proton exchange membrane device, the Ru/S NSs-400 can even sustain more than 300 h without obvious decay at the high current density of 250 mA cm-2 . The detailed investigations reveal that S doping not only changes the electronic structure of Ru via forming RuS coordination for high adsorption of reaction intermediates but also stabilizes Ru from over-oxidation. This strategy is also effective for improving the stability of commercial Ru/C and homemade Ru-based nanoparticles. This work offers a highly effective strategy to design high-performance OER catalysts for water splitting and beyond.

Multidentate Molecule Anchoring Halide Perovskite Surface and Regulating Crystallization Kinetics toward Efficient Light-Emitting Diodes.

Functional passivators are conventionally utilized in modifying the crystallization properties of perovskites to minimize the non-radiative recombination losses in perovskite light-emitting diodes (PeLEDs). However, the weak anchor ability of some commonly adopted molecules has limited passivation ability to perovskites and even may desorb from the passivated defects in a short period of time, which bring about plenty of challenges for further development of high-performance PeLEDs. Here, a multidentate molecule, formamidine sulfinic acid (FSA), is introduced as a novel passivator to perovskites. FSA has multifunctional groups (S≐O, C≐N and NH2 ) where the S≐O and C≐N groups enable coordination with the lead ions and the NH2 interacts with the bromide ions, thus providing the most effective chemical passivation for defects and in turn the formation of highly stable perovskite emitters. Moreover, the interaction between the FSA and octahedral [PbBr6 ]4- can inhibit the formation of unfavorable low-n domains to further minimize the inefficient energy transfer inside the perovskite emitters. Therefore, the FSA passivated green-emitting PeLED exhibits a high external quantum efficiency (EQE) of 26.5% with fourfold enhancement in operating lifetime as compared to the control device, consolidating that the multidentate molecule is a promising strategy to effectively and sustainably passivate the perovskites.

Structural stability, dihydrogen bonding, and pressure-induced polymorphic transformations in hydrazine borane.

Hydrazine borane (N2H4BH3) has attracted considerable interest as a promising solid-state hydrogen storage material owing to its high hydrogen content and easy preparation. In this work, pressure-induced phase transitions of N2H4BH3 were investigated using a combination of vibrational spectroscopy, X-ray diffraction, and density functional theory (DFT) up to 30 GPa. Our results showed that N2H4BH3 exhibits remarkable structural stability in a very broad pressure region up to 15 GPa, and then two phase transitions were identified: the first one is from the ambient-pressure Pbcn phase to a Pbca phase near 15 GPa; the second is from the Pbca phase to a Pccn phase near 25 GPa. As revealed by DFT calculations, the unusual stability of N2H4BH3 and the late phase transformations were attributed to the pressure-mediated evolutions of dihydrogen bonding frameworks, the compressibility and the enthalpies of the high-pressure polymorphs. Our findings provide new insight into the structures and bonding properties of N2H4BH3 that are important for hydrogen storage applications.

SLI-GNN: A Self-Learning-Input Graph Neural Network for Predicting Crystal and Molecular Properties.

Since the structures of crystals/molecules are often non-Euclidean data in real space, graph neural networks (GNNs) are regarded as the most prospective approach for their capacity to represent materials by graph-based inputs and have emerged as an efficient and powerful tool in accelerating the discovery of new materials. Here, we propose a self-learning-input GNN framework, named self-learning-input GNN (SLI-GNN), to uniformly predict the properties for both crystals and molecules, in which we design a dynamic embedding layer to self-update the input features along with the iteration of the neural network and introduce the Infomax mechanism to maximize the average mutual information between the local features and the global features. Our SLI-GNN can reach ideal prediction accuracy with fewer inputs and more message passing neural network (MPNN) layers. The model evaluations on the Materials Project dataset and QM9 dataset verify that the overall performance of our SLI-GNN is comparable to that of other previously reported GNNs. Thus, our SLI-GNN framework presents excellent performance in material property prediction, which is thereby promising for accelerating the discovery of new materials.

Layer-stacking of chalcogenide-terminated MXenes Ti2CT2(T = O, S, Se, Te) and their applications in metal-ion batteries.

Owning to limited supply of lithium for Li-ion batteries, the development of non-Li-ion batteries (such as Na+, K+Mg2+, Ca2+, and Al3+ion batteries) has attracted significant research interest. In this work, by means of the first-principles calculations, we systematically investigated the performance of chalcogenide-terminated MXenes Ti2CT2(T = O, S, Se, and Te) as electrodes for Li-ion and non-Li-ion batteries, as well as the layer-stacking and electronic properties of Ti2CT2. We find that the stacking type of O and Te terminated Ti2C multilayers with AA stacking differs from that of S and Se terminated Ti2C multilayers with AB stacking. More importantly, Ti2CO2monolayer can be potential anode material for Na- and K-ion batteries with high capacities and very low diffusion barriers (0.03-0.11 eV), while Ti2CS2and Ti2CSe2are promising anode materials with relatively low average open circuit voltages (OCVs) for Na-, K-, and Ca-ion batteries (0.4-0.87 V). Among these materials, Ti2CS2exhibits the largest ion capacity of 616 mAh g-1. These results of our work may inspire further studies of Ti2C-MXenes multilayers as electrodes for metal-ion batteries either experimentally or theoretically.

Significance of density functional theory (DFT) calculations for electrocatalysis of N2 and CO2 reduction reactions.

Density functional theory (DFT) based computational methods have shown great significance in developing high-performance electrocatalysts. In this perspective, we briefly summarized the state-of-the-art research progress of electrocatalysts for the nitrogen reduction reaction (NRR) and CO2 reduction reaction (CO2RR), which are important processes for the conversion of common molecules into value-added products. With the help of DFT calculations, various modulation strategies are employed to improve the catalytic activity and performance of NRR and CO2RR electrocatalysts. DFT calculations are performed to confirm the surface catalytic sites, evaluate the catalytic activity, reveal the possible reaction mechanisms, and design novel structures with high catalytic performance. By discussing the currently applied computational methods and conditions during the calculations, we outlined our concerns on the prospects and future challenges of DFT calculations in electrocatalysis studies.

Tuning low-temperature CO oxidation activities via N-doping on graphene-supported three-coordinated nickle single-atom catalysts.

Nitrogen doping is identified as an intriguing way to regulate graphene-supported single-atom catalysts (SACs) for heterogeneous catalysis. However, little theoretical effort has been directed towards exploring the activity trend in terms of N-doping level. In this study, we systematically investigated the N-doping effect on CO oxidation activities for graphene-supported three-coordinated Ni SACs (Ni-NxC3-x) in virtue of density functional theory (DFT) calculations and microkinetic modeling. We found that N-doping will shift the d-band center of single-atom Ni upwards, enhance the adsorption of intermediates, and tune the activation barrier to the overall reaction activities. Ni-N1C2 exhibits excellent catalytic performance with the highest total reaction rate comparable to that of noble metal SACs. These findings are helpful for understanding the N-doping influence and rationalizing the art of designing novel SACs for CO oxidation at low temperatures.

Monoatomic Platinum-Embedded Hexagonal Close-Packed Nickel Anisotropic Superstructures as Highly Efficient Hydrogen Evolution Catalyst.

The rational design of platinum (Pt) based nanostructures with specific crystal structure plays a significant role in their diverse applications. Herein, the anisotropic superstructures (ASs) of monoatomic Pt-embedded hexagonal close-packed nickel (hcp Ni) nanosheets were successfully synthesized for efficient hydrogen evolution in which an unusual dissociation-diffusion-desorption mechanism played a crucial role. The overpotential for the Pt/Ni ASs to reach the specific current density (10 mA cm-2) is 28.0 mV, which is much lower than that of conventional Pt/C catalyst (71.0 mV). Moreover, at the overpotential of 100 mV, the mass activity of 30.2 A mgPt-1 for the Pt/Ni ASs is 1060% greater than that in conventional Pt/C catalyst (2.6 A mgPt-1). This work provides a new approach to synthesize highly anisotropic superstructures embedded with monoatomic noble metals to boost their hopeful applications in catalytic applications.

Single-Atom Doping and High-Valence State for Synergistic Enhancement of NiO Electrocatalytic Water Oxidation.

The NiO-based electrocatalytic oxygen evolution reaction (OER) of water splitting is recognized as a promising approach to produce clean H2 fuel. However, the OER performance is still low, and especially, the overpotential is larger than 200 mV at the current density of 10 mA cm-2 . Herein, an Ir@IrNiO sample is prepared with single-atom (SA) Ir4+ doping and surface metallic Ir nanoparticles loaded onto the NiO. Owing to the bonding of the loaded Ir with surface-exposed Ni2+ , the nearby Ni atoms exist in the +3 valence state, that is, the surface-loaded Ir particles behave like a stabilizer for the Ni3+ sites. Under the synergistic effect of SA Ir4+ and high-valance-state Ni3+ , the Ir@IrNiO nanostructure effectively reduces the overpotential to 195 mV at a current density of 10 mA cm-2 . Moreover, it gives an Ir-content-normalized current density of 0.0457 A mgIr -1 , 72.1 times higher than that of the best commercialized IrO2 (6.33 × 10-4 A mgIr -1 ), under the condition of 1.5 V versus reversible hydrogen electrode. Operando Raman and X-ray absorption fine-structure (XAFS) measurements reveal that there are more surface-active species of Ni3+ , which adsorb and activate water molecules to form Ni3+ -*OH at low voltage, the intermediate of Ni4+ -•O is then formed at a relatively high bias voltage, and then the •O is transferred to the SA Ir4+ sites to generate Ir4+ -O-O with OH at increased voltage. This work can help design more SA-based highly active OER materials.

Compressive Strain in N-Doped Palladium/Amorphous-Cobalt (II) Interface Facilitates Alkaline Hydrogen Evolution.

The development of palladium-based catalysts for alkaline hydrogen evolution reaction (HER) is highly desired for renewable hydrogen energy systems, yet still challenging due to the strong palladium-hydrogen bond. Herein, the bottleneck is largely overcome by constructing a nitridation-induced compressively strained-interface N-doped palladium/amorphous cobalt (II) interface (N-Pd/A-Co(II)), which dramatically boosts HER performance in alkaline condition. The optimized catalyst with the compressive strain of 2.7% exhibits the higher activity with an overpotential of only 58 mV to achieve the current density of 10 mA cm-2 , much better than those of pure Pd (327 mV), and the state-of-art Pt/C (78 mV). Notably, it also shows excellent stability with negligible decline during a 30 h stability test. Detailed analyses reveal that the strong absorption of Hads on Pd can be efficiently reduced via the compressively strained N-doped Pd. And the amorphous Co(II) component accelerates the water dissociation. Consequently, the cooperative effect between the compressed N-doped Pd and amorphous Co(II) creates the impressive HER performance in alkaline condition, highlighting the importance of the functional interface to develop efficient electrocatalysts for HER and beyond.

First-principles materials simulation and design for alkali and alkaline metal ion batteries accelerated by machine learning.

The challenge of regeneration of batteries requires a performance improvement in the alkali/alkaline metal ion battery (AMIB) materials, whereas the traditional research paradigm fully based on experiments and theoretical simulations needs massive research and development investment. During the last decade, machine learning (ML) has made breakthroughs in many complex disciplines, which testifies to their high processing speed and ability to capture relationships. Inspired by these achievements, ML has also been introduced to bring a new paradigm for shortening the development of AMIB materials. In this Perspective, the focus will be on how this new ML technology solves the key problems of redox potentials, ionic conductivity and stability parameters in first-principles materials' simulation and design for AMIBs. It is found that ML not only accelerates the property prediction, but also gives physicochemical insights into AMIB materials' design. In addition, the final part of this paper summarizes current achievements and looks forward to the progress of a novel paradigm in direct/inverse design with the increasing number of databases, skills, and ML technologies for AMIBs.

IrOx @In2 O3 Heterojunction from Individually Crystallized Oxides for Weak-Light-Promoted Electrocatalytic Water Oxidation.

Multi-field coupling, especially photo-assisted electrocatalysis, has recently been studied to further improve the oxygen evolution reaction (OER). In this study, an n-type cubic In2 O3 semiconductor is employed for the first time to load IrOx species (Ir-In2 O3 mass ratio: 17.6 %). Consequently, the IrOx @In2 O3 heterojunction, which exhibits outstanding OER performance promoted by weak-light irradiation, is formed. Notably, IrOx (approximately 1.7 nm in size) and In2 O3 are observed to crystallize independently during heterogeneous nucleation with no Ir atoms doped in the In2 O3 lattice. This avoids Ir loss and ensures the full exposure of all Ir-based sites. The IrOx @In2 O3 heterojunction exhibits enhanced electrocatalytic water oxidation with overpotential values of 190 and 231 mV at current densities of 10 and 50 mA cm-2 , surpassing all IrOx -based catalyst results reported to date. Nano-sized IrOx on the surface, irradiated by the weak-light beam of LED-365 (1.8 mW cm-2 ), can be fully activated as an OER site. Moreover, the overpotential is further reduced to 176 and 210 mV to deliver the corresponding current. This work is anticipated to aid in the design of more efficient multi-field coupling OER systems.

Breaking Platinum Nanoparticles to Single-Atomic Pt-C4 Co-catalysts for Enhanced Solar-to-Hydrogen Conversion.

Effective transfer and utilization of the photogenerated electrons are a key factor for achieving highly efficient H2 generation by photocatalytic water splitting. Apart from the activity of the co-catalyst, the interface between the co-catalyst and semiconductor is of particular importance. Guided by DFT calculations, single-atom (SA) Pt doped carbon nitride (CN) is successfully synthesized for use as the co-catalyst to the semiconducting CuS. The catalyst system (Pt1-CN@CuS) exhibits an enhanced photocatalytic performance for water splitting with a H2 production rate of 25.4 µmol h-1 and an apparent quantum yield (AQY) of 50.3 % under the illumination of LED-530. Solar-to-hydrogen (STH) conversion efficiency is calculated to be 0.5 % under AM 1.5 illumination. This is the very first investigation of SA as the co-catalyst, which decreases the overpotential of CN during the water splitting and lowers interfacial resistance of the catalyst/co-catalyst and co-catalyst/electrolyte.

Fully Tensile Strained Pd3Pb/Pd Tetragonal Nanosheets Enhance Oxygen Reduction Catalysis.

While surface strain engineering in shaped and bimetallic nanostructures offers additional variables for manoeuvring the catalysis, manipulating isotropic strain distributions in nanostructures remains a great challenge to reach higher tiers of the catalyst's design. Herein, we report an efficient approach to construct a unique class of core/shell palladium-lead (Pd-Pb)/Pd nanosheets (NSs) and nanocubes (NCs) with homogeneous tensile strain along [001] on both the top-Pd and edge-Pd surfaces for boosting oxygen reduction reaction (ORR). These core/shell Pd-Pb/Pd NSs and Pd-Pb/Pd NCs exhibit over 160% and 140% increases in mass activity and over 114% and 98% increases in specific activity when compared with these unshelled counterparts, respectively. Especially, the Pd3Pb/Pd NSs show the ORR mass and specific activities of 0.57 A/mgPd and 1.31 mA/cm2 at 0.90 V versus reversible hydrogen electrode, which are 8.8 (6.5) and 9.4 (9.8) times higher than those of the commercial Pd/C (Pt/C), respectively. The valence band photoemission spectra and first-principles calculations collectively show that the tensile strained Pd shell results in an upshift of the d-band-center of Pd, weakening the chemisorption of oxygenated species due to the contribution of the antibonding orbital. In addition, the Pd3Pb/Pd NSs and NCs with intermetallic core and homogeneous few layers of Pd shell can sustain at least 20 000 potential cycles with negligible activity decay and composition changes. The present work provides a new direction for the design of highly active and stable catalysts for fuel cells and beyond.

In Situ Controlled Construction of a Hierarchical Supramolecular Chiral Liquid-Crystalline Polymer Assembly.

Hierarchical supramolecular chiral liquid-crystalline (LC) polymer assemblies are challenging to construct in situ in a controlled manner. Now, polymerization-induced chiral self-assembly (PICSA) is reported. Hierarchical supramolecular chiral azobenzene-containing block copolymer (Azo-BCP) assemblies were constructed with π-π stacking interactions occurring in the layered structure of Azo smectic phases. The evolution of chirality from terminal alkyl chain to Azo mesogen building blocks and further induction of supramolecular chirality in LC BCP assemblies during PICSA is achieved. Morphologies such as spheres, worms, helical fibers, lamellae, and vesicles were observed. The morphological transition had a crucial effect on the chiral expression of Azo-BCP assemblies. The supramolecular chirality of Azo-BCP assemblies destroyed by 365 nm UV irradiation can be recovered by heating-cooling treatment; this dynamic reversible achiral-chiral switching can be repeated at least five times.