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In respect to the van der Waals structures composed of two-dimensional transition metal dichalcogenides, the interlayer excitonic physics plays a determinative role in the exciting new phenomena and applications in such as photonics, optoelectronics and valleytronics. In this work, beyond the well-accepted, conventional indirect two-step process, we proved that the large interlayer polarization can cause the direct formation of interlayer excitons in MoSSe/WSSe. In MoSSe/WSSe, the interlayer exciton with a sizable oscillator strength is located at 1.49 eV, well below the characteristic intralayer excitons, with a significantly reduced exciton binding energy of 0.28 eV and an improved exciton lifetime of 2.25 ns.

Interfacing effects within emergent two-dimensional (2D) materials are of fundamental interest and are at the center of applications in nanoelectronics. Thus, out-of-plane and in-plane heterostructures as well as electronic heterostructures with phase boundaries and large-angle (60°) grain boundaries (GBs) of Janus ZrSSe and HfSSe are studied in this work using first-principles calculations. The out-of-plane heterostructures of T-ZrSSe and T-HfSSe illustrate quite weak interfacing interactions, thus the electronic properties are, unusually, more like the superposition of individual monolayers. The in-plane heterostructures of T-ZrSSe and T-HfSSe, interestingly, exhibit an indirect-direct band gap transition and type-II band alignment, which correspond to boosted optical properties and spatially separated excitons. For the in-plane electronic heterostructures that are constituted by T-ZrSSe and H-ZrSSe, semiconductor-metal crossover occurs due to the polar discontinuity across the T-H phase boundary, and they behave as one-dimensional metallic wires embedded in otherwise semiconducting Janus ZrSSe, creating a one-dimensional electron/hole gas. This also indicates a strategy for stabilizing the unstable and/or metastable monolayer

Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) hold great promise in electronics and optoelectronics due to their novel electronic and optical properties. In TMDCs, structural defects are inevitable and might play a decisive role in device performance. In this work, point defects, line vacancies, and 60° grain boundaries (GBs) are explored in 2D Janus MoSSe, a new member to the family of TMDCs, by means of the first-principles calculations. S and Se vacancies are found to be the most favorable point defects, and they tend to aggregate along the zigzag direction to form line vacancies. Comparing with isolated point defects, line vacancies induced in-gap states are more dispersive. In particular, 60° GBs behave as one-dimensional metallic quantum wires, as a consequence of the polar discontinuity. Thus, effectively controlling the formation of defects at nanoscale brings new electronic characteristics, providing new opportunities to broaden the applications of 2D TMDCs.

Surface plasmon resonance (SPR) is a special physical phenomenon exhibited by metal nanoparticles, which can convert light energy into chemical energy and thermal energy. The SPR effect has received extensive attention in the field of photochemical conversion, providing a new way to improve solar energy conversion efficiency. In this review, we briefly introduced the basic physical properties and mechanism of SPR, and summarized recent progress of plasmonic photocatalysts in the field of photochemistry, as well as the progress of single-particle spectroscopy in revealing the mechanism of hot carrier transport. Finally, we discussed the problems and development prospects in this field.

Hydrogenation of nitroaromatics is typically performed under harsh reaction conditions, which would bring safety issues and energy waste. The key for the hydrogenation reaction is to finely control...

Low-cost and abundant reserved nonmetallic plasmonic materials have been regarded as a promising substitute of noble metals for photocatalysis and surface-enhanced Raman scattering (SERS). In this ...

Plasmonic Bi2WO6 with strong localized surface plasmon resonance (LSPR) around the 500-1400 region is successfully constructed by electron doping. Oxygen vacancies on W-O-W (V1) and Bi-O-Bi (V2) sites are precisely controlled to obtain Bi2WO6-V1 with LSPR and Bi2WO6-V2 with defect absorption. Density functional theory (DFT) calculation demonstrates that the V1-induced energy state facilitates photoelectron collection for a long lifetime, resulting in LSPR of Bi2WO6. Photoelectron trapping on V1 sites is demonstrated by a single-particle photoluminescence (PL) study, and 93% PL quenching efficiency is observed. With strong LSPR, plasmonic Bi2WO6-V1 exhibits highly selective methane generation with a rate of 9.95 μmol g-1 h-1 during the CO2 reduction reaction (CO2-RR), which is 26-fold higher than 0.37 μmol g-1 h-1 of BiWO3-V2 under UV-visible light irradiation. LSPR-dependent methane generation is confirmed by various photocatalytic results of plasmonic Bi2WO6 with tunable LSPR and different light excitations. Furthermore, the DFT-simulated pathway of CO2-RR and in situ Fourier transform infrared spectra on the surface of Bi2WO6 prove that V1 sites facilitate CH4 generation. Our work provides a strategy to obtain nonmetallic plasmonic materials by electron doping.

For traditional cycloaddition reaction between CO2 and epoxide, high temperature and high pressure are usually needed. In this work, we introduce Lewis acid Bi atom into the porphyrin ring of a met...

Controlling two-dimensional (2D) valleytronics by external means is a major challenge to better information technology. Here, we demonstrate that introducing a ferroelectric-aided layer is an extra...

2D intercorrelated ferroelectrics, exhibiting a coupled in-plane and out-of-plane ferroelectricity, is a fundamental phenomenon in the field of condensed-mater physics. The current research is based on the paradigm of bi-directional inversion asymmetry in single-layers, which restricts 2D intercorrelated ferroelectrics to extremely few systems. Herein, we propose a new scheme for achieving 2D intercorrelated ferroelectrics using van der Waals (vdW) interaction, and apply this scheme to a vast family of 2D vdW materials. Using first-principles, we demonstrate that 2D vdW multilayers-for example, BN, MoS2, InSe, CdS, PtSe2, TI2O, SnS2, Ti2CO2 etc.- can exhibit coupled in-plane and out-of-plane ferroelectricity, thus yielding 2D intercorrelated ferroelectricsferroelectric physics. We further predict that such intercorrelated ferroelectrics could demonstrate many distinct properties, for example, electrical full control of spin textures in trilayer PtSe2 and electrical permanent control of valley-contrasting physics in four-layer VS2. Our finding opens a new direction for 2D intercorrelated ferroelectric research.

Antiferromagnetic (AFM) topological insulators (TIs) have recently attracted extensive attention as a platform for exploring prominent physical phenomena and innovative design of topological spintronic devices. Here, we theoretically demonstrate a topological switch between the normal insulator and AFM TI in two-dimensional NaMnBi quintuple layers. Using first-principles calculations to systematically investigate the structure, stability, magnetism, and electronic properties, we show that, while the AFM ordering is robust against external strain, the band gap and topology can be effectively tuned. Based on the spin Chern number, Wannier charge centers, and gapless edge states analysis, we identify that the AFM TI phase with out-of-plane magnetization is obtained even under a compressive strain as small as 0.58%. The presented results not only expand our understandings of magnetic topological states but also put forward potential applications in topological AFM spintronics.

Ni/TiO2 as a classic system has been widely studied in the traditional catalysis field including the water-gas shift reaction and selective oxidation/hydrogenation. However, in terms of the electrocatalytic hydrogen evolution reaction (HER), there is still a lack of systematic research on the actual synergistic promotion effect on the performance, and the influence of the host material on the electronic interaction between Ni and TiO2 is still unclear. Herein, we synthesized a series of Ni/TiO2 composites with different forms and tested the relevant HER performance. The results show that Ni/TiO2 exhibits much better HER performance than pure Ni and there is one type of electronic interaction between Ni and TiO2 in the composite with different forms, that is, electrons transfer from Ni to TiO2. However, the interaction strength is host dependent, and the composite with Ni as the host displays the strongest interaction, and therefore the best HER performance (46 mV at 10 mA cm−2).

Photocatalytic H2 generation has been believed to be a hopeful technology to deal with the current energy shortage issue. Among multifarious photocatalysts, graphitic carbon nitride (g-C3N4) has acquired enormous interests in virtue of its numerous advantages, such as peculiar physicochemical stability, favorable energy band structure and easy preparation. However, the insufficient light response range, low specific surface area, and inferior charge separation efficiency make its photocatalytic activity still unsatisfactory. In this work, the thermal exfoliation method was taken to prepare the thin g-C3N4 nanosheets with significantly improved specific surface area, which can afford more reaction sites and shorten the charge migration distance. Moreover, phosphorus (P) doping in g-C3N4 nanosheets can greatly expand its light absorption, improve the conductivity and charge-transfer capability. Due to the synergistic effect of these two strategies, the optimal H2 generation performance of P-doped g-C3N4 nanosheets came up to 1146.8 μmol g−1 h−1, which improved 15, 2.94 and 2.62 times compared to those of original bulk g-C3N4, thermally exfoliated g-C3N4 and P-doped bulk g-C3N4, respectively. The synergistic effect will inspire the design of other photocatalytic systems to achieve the efficient photocatalytic H2 generation activity.

A zirconium-based metal-organic framework containing boron (UiO-66-B) is prepared, which displays efficient photocatalytic H2O2 production. The H2O2 evolution rate is about 1002 μmol g-1 h-1, much higher than that of most known photocatalysts. Pristine UiO-66 displays a much lower activity (314 μmol g-1 h-1) under the same conditions, suggesting the significant role of boron. Both theoretical calculations and the combined experimental results verify the above conclusion, and the role of boron is ascribed to the following aspects: (1) enhanced O2 adsorption, (2) highly selective proton-coupled two-electron transfer, (3) faster carrier separation and surface charge transfer, and (4) faster generation but slower decomposition rates of H2O2. This work highlights key factors in the two-electron O2 reduction reaction (ORR), presents a deeper understanding of the role of boron in enhancing H2O2 production, and provides a new strategy for designing photocatalysts with excellent H2O2 evolution efficiency.

In the light of ultrahigh atom utilization, high catalytic activity and low cost, single-atom catalysts (SACs) have been garnering extensive attention in the field of electrochemistry. In recent studies, however, bifunctional SACs for water splitting are rare, and face the challenge of high overpotential. In this work, a series of transition metal (TM) atoms supported on two-dimensional (2D) H4,4,4-graphyne monolayer were verified to be bifunctional SACs for HER/OER and OER/ORR by first-principles calculations. It is interesting that Co@H4,4,4-GY and Pt@H4,4,4-GY could be applied as high-efficiency catalysts for water splitting with low overpotentials of 0.04/0.45 and 0.17/0.69 V for HER/OER, respectively. In addition, Ni@H4,4,4-GY as bifunctional SACs also exhibits desirable catalytic activity for OER/ORR with low overpotentials of 0.34/0.29 V, even superior to commercial IrO2 and RuO2. Our results reveal that TM–substrate coordination and local electronic property show significant effects on the catalytic properties for HER/OER/ORR, and the d band center as an effective descriptor could be adopted to optimize the catalytic performance of the catalysts.

Single-atom catalysts (SACs) have been intensively explored for many electrochemical reactions, but rarely in nonaqueous alkali oxygen batteries. A picture (activity trend, reaction mechanism and design principle) of SACs for nonaqueous alkali oxygen batteries remains to be built up. Here, using first-principles, we construct such a picture by systematically investigating the catalytic activities of SACs of transition metal–porphyrin (TM–porphyrin) in Li–O2 batteries. Through fully exploring the possible reaction pathways, we reveal the reaction mechanism and chemical compositions of reaction products, and find that Fe/Co/Ni/Cu–porphyrin are promising cathode electrocatalysts for Li–O2 batteries. The influences of various axial ligands on their catalytic performances are also studied. More importantly, based on the catalytic activities of free and axial ligand adsorbed Fe/Co/Ni/Cu–porphyrin, the adsorption free energy of LiO2 is identified as a simple activity descriptor suitable for these cathode electrocatalysts. We further show that such a descriptor is also applicable for the catalytic activities of Fe/Co/Ni/Cu–porphyrin in Na–O2 batteries. Our work not only provides a series of highly efficient SACs for alkali oxygen batteries, but also presents a universal design principle.

NH3 synthesis and NO removal are two of the most attractive and challenging processes in electrochemistry. Current research efforts mainly focus on them separately, while the direct electrochemical reduction of NO to NH3 has been less explored. Herein, based on first-principles calculations, we propose a metal-free electrocatalyst, namely, P atom doped single-layer C2N, as a promising candidate system for achieving the direct electroreduction of NO to NH3. Particularly, double P doped C2N (2P@C2N) exhibits excellent catalytic activity and high selectivity, which correlates with the sp3 hybridization of the P atom. Moreover, our microkinetic modeling analysis shows that the turnover frequency of NO reduction to NH3 on 2P@C2N is as large as 8.9 × 105 per s per site at 400 K, suggesting that it exhibits an ultra-fast reaction rate. Our study provides not only the first metal-free electrocatalyst for NO removal, but also an effective alternative avenue for ammonia synthesis.

Magnetic topological states open up exciting opportunities for exploring fundamental topological quantum physics and innovative design of topological spintronics devices. However, the nontrivial topologies, for most known magnetic topological states, are usually associated with and may be heavily deformed by fragile magnetism. Here, using a tight-binding model and first-principles calculations, we demonstrate that a highly robust magnetic topological insulator phase, which remains intact under both ferromagnetic and antiferromagnetic configurations, can emerge in two-dimensional EuCd2Bi2 quintuple layers. Because of spin–orbital coupling, an inverted gap with intrinsic band inversions occuring simultaneously for up and down spin channels is obtained, accompanied by a nonzero spin Chern number and a pair of gapless edge states, and remarkably the magnitude of the nontrivial band gap for EuCd2Bi2 reaches as much as 750 meV. Moreover, the robustness of the magnetic TI phase is further confirmed by rotating the magnetization directions, indicating that EuCd2Bi2 represents a promising material for understanding and utilizing the topological insulating states in two-dimensional spin–orbit magnets.

In this work, Fe-BHT is identified as the most efficient catalyst for the hydrogen evolution reaction (HER) among the TM-BHTs (TM = Sc, Ti, V, Cr, Mn, Fe, Co, and Ni), with an overpotential as low as 0.09 V. It is found that Fe dz2 orbitals do not participate in the bonding with surrounding S/N atoms in the FeX4 active center but are bonding states for hydrogen adsorption. In accordance with our results, a steric effect determined energy gap acts as an efficient descriptor for the HER activity, which has never been discussed in previous studies. In addition, strain engineering proves the proposed steric effects, which also highlights the importance of the point group symmetry of active centers.

Utilizing a photoelectrochemical (PEC) fuel cell to replace difficult water oxidation with facile oxidation of organic wastes is regarded as an effective method to improve the H

The realization of magnetic skyrmions in nanostructures holds great promise for both fundamental research and device applications. Despite recent progress, intrinsic magnetic skyrmions in two-dimensional lattice are still rarely explored. Here, using first-principles calculations and Monte Carlo simulations, we report the identification of spontaneous magnetic skyrmions in single-layer CrInX

Direct ammonia (NH

In this study, a novel NiCoP-CeO

The rate-determining step of the photoelectrochemical (PEC) water splitting is the water oxidation reaction at the photoanode, which is 4 orders of magnitude slower than the water reduction reactio...

Exploring two-dimensional valleytronic crystals with large valley-polarized state is of considerable importance due to the promising applications in next-generation information related devices. Here, we show first-principles evidence that single-layer NbX2 (X = S, Se) is potentially the long-sought two-dimensional valleytronic crystal. Specifically, the valley-polarized state is found to occur spontaneously in single-layer NbX2, without needing any external tuning, which arises from their intrinsic magnetic exchange interaction and inversion asymmetry. Moreover, the strong spin-orbit coupling strength within Nb-d orbitals renders their valley-polarized states being of remarkably large (NbS2 ∼ 156 meV/NbSe2 ∼ 219 meV), enabling practical utilization of their valley physics accessible. In additional, it is predicted that the valley physics (i.e., anomalous valley Hall effect) in single-layer NbX2 is switchable via applying moderate strain. These findings make single-layer NbX2 tantalizing candidates for realizing high-performance and controllable valleytronic devices.

In recent years, the preservation of fruits and vegetables in cold storage has become an issue of increasing concern, ethylene plays a leading role among them. We found ZnO has the effect of degrading gaseous ethylene, however its effect is not particularly satisfactory. Therefore, we used simple photo-deposition procedure and low-temperature calcination method to synthesize Au, Ag, and AuAg alloy supported ZnO to improve the photocatalytic efficiency. Satisfactorily, after ZnO loaded with sole Au or Ag particles, the efficiency of ethylene degradation was 17.5 and 26.8 times than that of pure ZnO, showing a large increase in photocatalytic activity. However, the photocatalytic stability of Ag/ZnO was very poor, because Ag can be easily photooxidized to Ag2O. Surprisingly, when ZnO was successfully loaded with the AuAg alloy, not only the photocatalytic activity was further improved to 94.8 times than that of pure ZnO, but also the photocatalytic stability was very good after 10 times of cycles. Characterization results explained that the Au-Ag alloy NPs modified ZnO showed great visible-light absorption because of the surface plasmon resonance (SPR) effect. Meanwhile, the higher photocurrent density showed the effective carrier separation ability in AuAg/ZnO. Therefore, the cooperative action of plasmonic AuAg bimetallic alloy NPs and efficient carrier separation capability result in the outstanding photoactivity of ethylene oxidation. At the same time, the formation of the alloy produced a new crystal structure different from Au and Ag, which overcomes the problem of poor stability of Ag/ZnO, and finally obtains AuAg/ZnO photocatalyst with high activity and high stability. This work proposes a new concept of using metal alloys to remove ethylene in actual production.

In this study, ZnO flowers were synthesized by a one-step hydrothermal method. On this basis, the ZnS nanoparticles were anchored uniformly on the surface of ZnO by a solution recrystallization strategy to form a ZnO@ZnS core-shell structure. A further increase in thiourea leads to the formation of a ZnS hollow structure, which is due to the Kirkendall effect. Throughout the process, the flower-like structure has not changed. The effects of the ZnS with different loadings on the morphology, crystallization properties, specific surface area, photoelectric response, and photocatalytic activity of the ZnO were investigated. The optimum ZnO@ZnS composite exhibited excellent photocatalytic activity of 757.07 μmol g−1 of H2 under simulated solar light irradiation. The results show that depositing an appropriate amount of ZnS nanoparticles on ZnO nanorods can effectively improve charge transfer. The charge transfer and the high specific surface area of the catalyst enhance the activity of photocatalytic H2 production.

Two-dimensional valleytronics, using the valley index of carriers to perform logic operations, serves as the basis of the next-generation information technologies. Here, using first-principles calc...

Two-dimensional electrocatalytic materials for hydrogen evolution reaction (HER) have attracted considerable attention recently. However, most of the reported systems exhibit an inert basal plane, and extra engineering are needed to trigger the activity, greatly hindering their practical applications. Herein, using first-principles calculations, we identify a family of promising HER catalytic materials with high intrinsic activity in MXene Ti4X3O2 (X = C, N). We find that Ti4X3 are terminated by a mixture of OH* and O* under standard condition by plotting Pourbaix diagram. The adsorption of atomic hydrogen on Ti4X3O2 exhibits a low Gibbs free energy difference, and the obtained activity barrier of Volmer-Heyrovsky step for Ti4N3O2 is only 30 meV, which indicates the excellent intrinsic HER activity. Furthermore, we explore the HER activity of Ti4X3O2 in aqueous solution through applying biaxial strain, and find that the low Gibbs free energy is well preserved, demonstrating the high stability of the intrinsic HER activity of Ti4X3O2 in solution environment.

Oxygen vacancies are usually thought to be beneficial for photogenerated charge separation. In this work, the oxygen vacancies in ov-Bi2 O3 (Bi2 O3 with oxygen vacancy) were found to be able to produce 1 O2 in the dark owing to chemical adsorption. The oxygen vacancies were further found to be responsible for ov-Bi2 O3 exhibiting higher 1 O2 generation under light irradiation with 1 O2 as the only reactive oxygen species (ROS) than Bi2 O3 with 1 O2 , H2 O2 , and others as the ROS. The photocatalytic activity was investigated for the selective photo-oxidation of phenyl methyl sulfide to phenyl methyl sulfoxide and phenyl alcohol to benzaldehyde. In either case, ov-Bi2 O3 displayed better performance than Bi2 O3 , suggesting the significant role of oxygen vacancies in modulating the photocatalytic oxidation properties. This work provides an alternative approach to obtain singlet oxygen, which may guide further design of photocatalysts with high efficiency and selectivity towards photocatalytic organic synthesis.

Trifunctional electrocatalysts with high activity for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and Na–O2 battery are eagerly desirable for electrochemical energy applic...

TiO2 nanospheres with high specific surface area and good crystallinity were prepared by a hydrothermal method using urea as the capping agent and isopropanol as the solvent. The capping agent effectively controlled the morphology of TiO2 nanospheres and led to improved crystallinity. Using a solvent with a long carbon chain, such as isopropanol, also promoted the formation of TiO2 nanospheres. TiO2 nanospheres with different morphologies were prepared by adjusting the amount of urea. It was found that when TiO2-0.6 was used as the photocatalyst, highest rates of degradation of both methylene blue and rhodamine B under ultraviolet-visible light were observed. Moreover TiO2-0.6 also had the largest hydrogen production efficiency among the different TiO2 samples tested. Thus, TiO2 nanospheres have great development potential and application prospects in environmental management and new modes of energy utilization.

The oxygen evolution reaction (OER) plays a vital role in various energy conversion applications. Up to now, the highly efficient OER catalysts are mostly based on noble metals, such as Ir- and Ru-based catalysts. Thus, it is extremely urgent to explore the non-precious electrocatalysts with great OER performance. Herein, a simple electrodeposition combined with hydrothermal method is applied to synthesize a non-precious OER catalyst with a three-dimensional (3D) core-shell like structure and excellent OER performance. In our work, NiFe layered double hydroxide (LDH) was electrodeposited on Ni3S2 nanosheets on nickel foam (NF), which exhibits a better performance compared with RuO2, and a low overpotential of 200 mV is needed to reach the current density of 10 mA/cm2 in 1 M KOH. Notably, the Ni3S2/NiFe LDH only need an overpotential of 273 mV to reach the current density of 200 mA/cm2.

Electrochemical water splitting is considered as an effective and promising method to produce the ideal hydrogen energy to solve the energy crisis and environmental pollution problems. Herein, we s...

Magnetic topological insulators (TIs), including the quantum anomalous Hall effect and antiferromagnetic TIs, have attracted significant attention owing to the exotic properties they give rise to, however, ferromagnetic TIs with gapless surface/edge states and a nonzero topological invariant have not been reported so far. Here, we show that a ferromagnetic topological insulating phenomenon is possible in a single layer honeycomb lattice on the basis of perturbation theory and model Hamiltonian analyses. As a probable candidate for the experimental realization of this phenomenon, we propose a hypothetical single-layer Na2MnPb with supporting evidence based on first-principles calculations. The topological nature of the single-layer Na2MnPb is confirmed by calculating the Wannier charge center, the spin Chern number, and the gapless edge states.

The development of two-dimensional (2D) organic catalysts with intriguing catalytic activity for the nitrogen reduction reaction (NRR) still remains challenging. Here, we exploit a series of experimentally feasible nitrogen-free metal–organic frameworks (MOFs) of transition metal–benzenehexathiol (TM–BHT, with TM being Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd and Ag) for dinitrogen (N2) fixation and ammonia (NH3) synthesis. Through the first-principles screening and microkinetic analyses, we find that TMS4 centers can serve as electron reservoirs for associative N2 hydrogenation to overcome energy efficiency versus rate trade-offs. It turns out that among these candidates, Mo–BHT exhibits the lowest limiting potential and highest turnover frequency (TOF) competitive to that of benchmark Fe catalysts. In light of the synergistic effects between the active center and ligand, the high performance of Mo–BHT toward the NRR was rationalized. In the context of searching for efficient NRR catalysts, our results demonstrate the great possibilities of MOFs as an emerging avenue for NH3 synthesis under ambient conditions, and provide a strategy for the design of catalysts by appropriately tuning the active centers and ligands.

With the advent of two-dimensional materials, it is now possible to realize p–n junctions at the ultimate thickness limit. However, the performance of p–n junctions significantly degrades as their thicknesses approach the nanoscale and the conventional fabrication processes, such as implantation and doping, become invalid. Here, using first-principles calculations, we report a novel strategy to realize self-doped p–n junctions in two-dimensional materials. By stacking triple-layer In2X3 (X = S, Se), an atomically thin p–n junction forms naturally without any additional modulation involved, which is attributed to the asymmetric structure-induced self-doping. In addition, such self-doped p–n junctions are also obtained when sandwiching single-layer and double-layer In2S3 in-between graphene layers. More interestingly, the outmost layers in all these systems become metallic due to the self-doping, achieving natural low-resistance contact. This work illustrates a straightforward method for developing more effective electronic and optoelectronic nanodevices.

As far as we know, the CO2 photoconversion reaction with H2O includes two important steps. One step is CO2 photoreduction (photogenerated electrons) while the other step is the oxidation of water (photogenerated holes). It is obvious that the oxidation of water is also the key step in the CO2 photoconversion reaction. However, little research has been done to improve the oxidation of water, thereby indirectly improving the photocatalytic CO2 reduction property of TiO2. Moreover, CO2 adsorption capacity is also considered as an important limiting factor for the CO2 photoconversion activity. Therefore, in this paper, CoPi (an amorphous cobalt-phosphate-based material) with high CO2 adsorption capacity was successfully immobilized on the surface of TiO2 nanosheets and served as a hole-cocatalyst to trap holes, thereby delaying the recombination of photogenerated electrons and holes and providing more CO2 gas to take part in the CO2 reduction reaction. Hence, the TiO2/CoPi exhibited much better CO2 photoconversion performance in water compared to pristine TiO2.

New types of electrocatalysts with high activity and selectivity are essential for advancing sustainable hydrogen and ammonia productions. Herein, through extensive first-principles calculations, we systematically investigated the potential of molecular nanowires (i.e., transition metal-phthalocyanine and transition metal-porphyrin nanowires), a broadly studied and experimentally synthesized class of frameworks as electrocatalysts for hydrogen and ammonia production. Our computations reveal that among the 20 candidate systems, Co-phthalocyanine/porphyrin nanowires are found to be the superior electrocatalysts for HER, while Ti-porphyrin and Mo-phthalocyanine/porphyrin nanowires exhibit excellent NRR activity with high selectivity and efficiency. Such catalytic activities primarily correlate to the electronic configurations of their d orbitals. Our study not only extends the electrocatalysis to molecular nanowire systems for the first time but also provides a design principle for accelerating the search for molecular nanowire catalysts.