Intimate Interfacial Interaction Research Articles

Enhanced Supercapacitor Performance by Harnessing Carbon Nanoparticles and Colloidal SnO2 Quantum Dots

The creation of effective supercapacitor materials is still a priority in the quest to improve energy storage technology. Herein, we present a novel nanocomposite composed of carbon nanoparticles (CNPs) and colloidal SnO2 quantum dots (c-SQDs) or colloidal SnO2 ultrasmall nanoparticles, synthesized through a facile sonochemical-assisted hydrothermal approach. The XRD and XPS analyses confirmed the successful synthesis and composition of the CNP/c-SQD nanocomposite. Morphology studies revealed a well-dispersed morphology with intimate interfacial interactions between the CNPs and c-SQDs. Specifically, the nanocomposite exhibited a high specific capacitance of 569 F/g at a current density of 1 A/g, surpassing conventional carbon-based supercapacitors. Furthermore, the nanocomposite displayed excellent stability with 99% capacity retention after 5000 cycles, indicative of its superior cyclability. These results underscore the potential of the CNP/c-SQD nanocomposite as a promising electrode material for high-performance supercapacitor applications, offering enhanced charge storage capacity, stability, and cyclability. This study contributes to the advancement of energy storage technologies, paving the way for the development of efficient and sustainable electrochemical energy storage devices.

Protonated g-C3N4/oxygen-doped g-C3N4 S-scheme homojunction fabricated by electrostatic self-assembly for photocatalytic hydrogen evolution and tetracycline hydrochloride degradation

S-scheme photocatalytic systems with high redox ability and separation efficiency of photoexcited charge carriers supply considerable prospects for environmental optimization and sustainable energy development. However, coupling well-suited reduction and oxidation components for target reactions remains a challenge worth exploring. Herein, an efficient S-scheme system for H2 generation and tetracycline hydrochloride (TCH) photodegradation based on protonated g-C3N4 (PCN) coupling with oxygen-doped g-C3N4 (OCN) is fabricated via a facile electrostatic self-assembly strategy. Intimate interfacial interactions originating from the ultrathin nanostructure and staggered energy band arrangement for the S-scheme charge transfer pathway provide compelling advantages for the highly efficient separation of photoinduced electron-hole pairs in the as-designed PCN/OCN homojunction. The in-situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) techniques and electron paramagnetic resonance (EPR) measurements are applied to confirm the successful construction and the validity of the S-scheme charge transfer pathway. The obtained PCN/OCN composites with optimal ratio achieve a decent H2 generation rate of 6184.7 μmol g−1 h−1 outpacing the single PCN by approximately 4.8-fold, and 90.5 % TCH photodegradation efficiency is also realized within 90 min. This work provides a delicate fresh round of elevation for the exploration of an effective photocatalytic system.

Boosted photocatalytic accomplishment of 3D/2D hierarchical structured Bi4O5I2/g-C3N4 p-n type direct Z-scheme heterojunction towards synchronous elimination of Cr(VI) and tetracycline

The threats posed by heavy metal ions and antibiotics present in natural aqueous environments have been a serious cause of concern across the globe. The synchronous elimination of these contaminants through visible light responsive semiconductor mediated photocatalysis is a suitable strategy to solve this problem. However, designing proficient photocatalysts for the said purpose is a crucial task. Herein, hierarchical 3D/2D architectures of Bi4O5I2/g-C3N4 p-n type direct Z-scheme heterojunction photocatalysts (BOCNs) were fabricated by a two-step solvothermal-calcination approach. The characterisation of BOCNs by XRD, FTIR, XPS, SEM, TEM, HRTEM, LSV and MS techniques corroborated the robust heterojunction formation between Bi4O5I2 and g-C3N4. The presence of g-C3N4 and application of high treatment temperature (400 °C) assisted the formation of BiOC bond which is responsible for the development of an intimate interfacial interaction in BOCN. The heterostructured photocatalyst (BOCN3) demonstrated higher rate constant (kCr(VI)/synchronous) of 0.068 min−1 for Cr(VI) detoxification and that (kTCH/synchronous) of 0.075 min−1 for TCH degradation synchronously with respect to the reported values. The determined rate constants are about 1.8 folds greater than those were observed in isolated systems. The expedited photocatalytic activity can be ascribed to its wide visible light response, minimum charge recombination rate and increased redox ability. These are resulted from the synergistic effect of hierarchical 3D/2D architecture construction, existence of strong BiOC interfacial bond, p-n heterojunction formation and prevalence of direct Z-scheme charge transfer principle. The synchronous elimination of Cr(VI) and TCH over BOCN3 up to the fifth consecutive cycle without any appreciable change in photoactivity signified its enhanced stability and reusability. The plausible mechanism for the spectacular photocatalytic performance of BOCN3 was proposed.

Synergistic Effect of Nickel Nanoparticles Dispersed on MOF-Derived Defective Co3O4 In Situ Grown over TiO2 Nanowires toward UV and Visible Light Driven Photothermal CO2 Methanation.

Catalytic CO2 hydrogenation is an effective approach to producing clean fuels, but this process is expensive, in addition to the low efficiency of catalysts. Thus, photothermal CO2 hydrogenation can effectively utilize solar energy for CH4 production. Metal-organic framework (MOF) derived materials with a controlled structure and morphology are promising to give a high number of active sites and photostability in thermal catalytic reactions. For the first time, a novel heterostructure catalyst was synthesized using a facile approach to in situ grow MOF-derived 0D Co3O4 over 1D TiO2 nanowires (NWs). The original 3D dodecahedral structure of the MOF is engineered into novel 0D Co3O4 nanospheres, which were uniformly embedded over Ni-dispersed 1D TiO2 NWs. In situ prepared 10Ni-7Co3O4@TiO2 NWs-I achieved an excellent photothermal CH4 evolution rate of 8.28 mmol/h at 250 °C under low-intensity visible light, whereas UV light treatment further increased activity by 1.2-fold. UV irradiations promoted high CH4 production while improving the susceptibility of the catalyst to visible light irradiation. The photothermal effect is prominent at lower temperatures, due to the harmonization of both solar and thermal energy. By paralleling with mechanically assembled 10Ni-7Co3O4/TiO2 NWs-M, the catalytic performance of the in situ approach is far superior, attributing to the morphological transformation of 0D Co3O4, which induced intimate interfacial interactions, formation of oxygen vacancies and boosted photo-to-thermal effects. The co-existence of metallic/metal oxide Ni-Co provided beneficial synergies, enhanced photo-to-thermal effects, and improved charge transfer kinetics of the composite. This work uncovers a facile approach to engineering the morphology of MOF derivatives for efficient photothermal CO2 methanation.

Nanoarchitecture of a Ti3C2@TiO2 Hybrid for Photocatalytic Antibiotic Degradation and Hydrogen Evolution: Stability, Kinetics, and Mechanistic Insights.

Designing of a visible-light-driven semiconductor-based heterojunction with suitable band alignment and well-defined interfacial contact is considered to be an effective strategy for the transformation of solar-to-chemical energy and environmental remediation. In this context, MXenes have received tremendous attention in the research community due to their merits of abundant derivatives, elemental composition, excellent metallic conductivity, and surface termination groups. Meanwhile, a facile synthetic strategy for MXene-derived TiO2 nanocomposites with stable framework and higher photocatalytic activity under visible-light irradiation still remains a challenge for researchers. Herein, we report a novel synthetic strategy of preparing a two-dimensional Ti3C2@TiO2 nanohybrid by a facile reflux method under acidic conditions. In this oxidation reaction, protonation of the hydroxyl terminal group of MXene creates Ti more electrophilic and susceptible to an oxidative nucleophilic addition reaction with the presence of both water and oxygen. The physicochemical properties of the nanohybrid Ti3C2@TiO2 were verified by varieties of characterization techniques. High-resolution transmission electron microscopy and X-ray photoelectron spectroscopy analysis specifically elucidated the intimate interfacial interaction between Ti3C2 and TiO2. The optimized Ti3C2@TiO2-48 h photocatalyst exhibited the highest tetracycline hydrochloride (TCH, 90% in 90 min) degradation efficiency in comparison to pristine TiO2 with a rate constant (k) of 0.02463 min-1. The major contribution of •O2- and •OH radicals throughout photocatalytic TCH degradation was confirmed by the trapping experiment. Moreover, the photocatalyst showed the highest hydrogen generation rate of 140.8 μmol h-1 along with an apparent conversion efficiency of 2.2%. The excellent photocatalytic activity of Ti3C2@TiO2 originated from the superior electrical conductivity of cocatalyst Ti3C2, which facilitated spatial photogenerated e-/h+ separation and transfer at the Ti3C2 MXene@TiO2 interface. Overall, this research work will describe a promising protocol of designing MXene-derived photocatalysts toward efficient environmental remediation and wastewater treatment applications.

Interfacial charge separation of nickel tungstate anchored on g-C3N4 heterojunction stimulates visible-light driven direct Z-scheme photoelectrochemical hydrogen evolution

Active photocathodes are required for the photo(electro)chemical hydrogen evolution reaction (PEC-HER) in a highly efficient solar-to-hydrogen fuel conversion process aided by solar assisted water splitting. Here, we used a simple one-pot solvothermal method to prepare NiWO4/g-C3N4 nanocomposites for PEC-HER using low-cost, metal-free photocatalysts such as graphitic carbon nitride (g-C3N4) and nickel tungstate (NiWO4). Subsequently, the physicochemical and optoelectronic nature of the as-synthesized materials were studied by spectroscopic methods. As part of a direct Z-scheme heterogeneous mechanism, the photoactive module, g-C3N4 was blended with NiWO4 in varying ratios to enhance the efficiency of charge separation in PEC-HER. As expected, the established NiWO4/g-C3N4 nanocomposite demonstrates an enhanced photo(electro)catalytic activities compared to the single components. It is firmly due to the presence of intimate interfacial interaction between g-C3N4 and NiWO4, which further supports the existence of electrons in the conduction band of g-C3N4 and holes in the valence band of NiWO4. The prepared NiWO4/g-C3N4 nanocomposite with 15 wt% of g-C3N4 showed an enhanced photocurrent density of 167.81 mA cm−2, which is higher than that of other prepared photo(electro)catalysts and confirms its excellent charge separation efficiency as well as very low electron-hole recombination rate. Besides, the photoelectrochemical activities of the prepared materials were analysed through a PEC-HER, revealing that the developed NiWO4/g-C3N4 nanocomposite as photocathode requires a low overpotential of 0.048 V to reach the current density of 10 mA cm−2 and a Tafel slope of 43 mV dec−1, indicating the superiority of the photo(electro)catalyst. In addition, the NiWO4/g-C3N4 photocathode exhibits excellent performance for PEC-HER with higher stability.

Modulating interfacial charge redistribution of Ni2P/CuCo2S4 p-n nano-heterojunctions for efficient electrocatalytic overall water splitting

Fabricating effective yet inexpensive catalysts is an important target in the research of water electrolysis and clean energy generation. Key challenges still remaining in this area are the rich density of surface-active sites, efficient interfacial charge transfer and improved reaction kinetics. Herein, Ni2P/CuCo2S4 p-n junctions are constructed via an in situ hydrothermal growth of Ni2P nanoparticles on CuCo2S4 nanosheets. Extensive X-ray photoelectron, optical absorption and electrochemical spectroscopy studies coupled with density functional theory calculations provide a mechanistic understanding of the electrochemical behaviour of these catalysts. The integrated Ni2P/CuCo2S4 p-n junctions, owing to the intimate interfacial interactions, offer interesting possibilities to purposively modulate the electronic structure of active sites at the interface, and thus to improve the hydrogen adsorption energetics and electrochemical reaction kinetics. As a result, the catalyst with 30 wt% Ni2P content displays high intrinsic electrocatalytic activity, requiring overpotentials of 183 and 360 mV to deliver 10 mA cm−2 for HER and 40 mA cm−2 for OER in alkaline media, respectively, far lower than those of individual Ni2P (400 and 520 mV) and CuCo2S4 (348 and 380 mV), further showing remarkable durability for 30 h. In addition, an alkaline two-electrode water electrolyzer assembled by Ni2P/CuCo2S4 nano-heterojunctions exhibits a relatively low cell potential of 1.67 V at 10 mA cm−2. These Ni2P-modified CuCo2S4 heterostructures demonstrate great potential for renewable hydrogen production technologies, including water electrolysis.

Hierarchically porous polyimide aerogel fibers based on the confinement of Ti3C2Tx flakes for thermal insulation and fire retardancy

Thermally insulating and flame-resistant fibers/textiles have drawn enormous attention attributing to their great application prospects in personal thermal management and protective clothing. Nevertheless, conventional natural fibers and synthetic fibers are insufficient for advanced thermal regulation. Herein, an in-situ polymerization method and wet-spinning technique are employed for the continuous and scalable fabrication of polyimide (PI) aerogel fibers utilizing monolayered Ti3C2Tx flakes as the pore-generating agents. Benefiting from the intimate interfacial interaction between MXene and the macromolecular chains, hierarchical porosity is constructed in the composite aerogel fibers due to the confinement of the interconnected PAA/Ti3C2Tx networks during liquid-solid phase separation. As a result, the PI/Ti3C2Tx aerogel fibers manifest significantly enhanced mechanical properties (tensile strength of 26 MPa), large specific surface area (145 m2 g−1), excellent flame resistance, and remarkable thermal insulation performance (with a low thermal conductivity of 36 mW m−1 K−1), which can be readily weaved into flexible textiles for practical thermal regulating applications. This approach is expected to pave a new way for the fabrication and application of high-performance thermal insulating fibers and textiles.

2D/2D Inorganic/Organic Hybrid of Lead-Free Cs2AgBiBr6 Double Perovskite/Covalent Triazine Frameworks with Boosted Charge Separation and Efficient CO2 Photoreduction.

Heterojunction construction, especially the inorganic/organic hybrids, is regarded as a universal and effective strategy to achieve high-performance photocatalysts. Herein, a 2D/2D inorganic/organic hybrid photocatalyst was constructed by the electrostatic self-assembly of the lead-free double-perovskite of Cs2AgBiBr6 nanosheets (NSs) and covalent triazine framework (CTF) NSs. The resultant Cs2AgBiBr6/CTF-1 (CABB/CTF-1) hybrid possessed a large surface-to-surface contact area, ensuring intimate interfacial interaction and efficient charge transfer/separation. Meanwhile, the periodical pore structure of CTF-1 endowed the CABB/CTF-1 hybrid with enhanced CO2 adsorption/activation capacity. Consequently, the 2D/2D CABB/CTF-1 hybrid exhibited a remarkable photocatalytic performance toward CO2 reduction. Based on the band structure analysis and various characterization techniques, for example, X-ray photoelectron spectra and electron spin resonance, an S-scheme charge transfer mechanism was proposed. This study presents a new protocol for designing 2D/2D inorganic/organic hybrid photocatalytic systems, which hold great potentials in solar fuel applications.

Constructing ultrathin defective Co3O4/MoS2 nanosheets based 2D/2D heterojunction toward room temperature NH3 detection

Ultrathin 2D/2D face-to-face heterostructures have shown promising applications in gas sensing devices. Synthesis of ultrathin 2D/2D metal oxide/MoS2 based heterostructures, however, remains challenging probably due to the difficulty in preparing ultrathin 2D metal oxides. Here, ultrathin defective Co3O4/MoS2 nanosheets (NSs) with large heterointerfaces and high specific surface area are prepared via in-situ growth of MoS2 on salt-template-synthetic Co3O4 NSs. The as-obtained Co3O4/MoS2 sensor exhibits a high response value of 2.1 toward 5 ppm NH3 at room temperature, outperforming most sensors based on metal oxide/MoS2 reported hitherto. Moreover, the ultrathin defective Co3O4/MoS2 NSs sensor presents excellent selectivity and long-term stability. The excellent gas sensing performances of the Co3O4/MoS2 based sensor are attributed to the presence of rich defects and intimate interfacial electronic interaction, which ensures abundant active adsorption sites and rapid electrons transfer. Our method demonstrates a versatile integration strategy to construct 2D/2D heterostructures for innovative applications including but not limited to the gas sensing fields.

Vanadium pentoxide–dibismuth trioxide nanosheets for efficient photoelectrochemical water splitting: Effect of applied bias on charge transfer kinetics

V2O5-Bi2O3 nanosheets were synthesized using a facile technique, and the effects of the heterostructure on the generation of photocurrents and charge kinetics under dark/light conditions were investigated. The intimate interfacial interaction between V2O5 and Bi2O3 in the V2O5–Bi2O3 nanosheets resulted in a significantly high and stable photocurrents of approximately 1.7 × 10-4 Acm−2 for 1000 s, which is 5.4 and 14.4 times higher than that of pure V2O5 and Bi2O3 nanosheets. The synergetic effect of pure V2O5 and Bi2O3 on the charge transfer kinetics of V2O5–Bi2O3 photoelectrodes at different applied bias potentials was systematically analyzed.

Core-shell structured Z-scheme Ag2S/AgIO3 composites for photocatalytic organic pollutants degradation

Constructing direct Z-scheme system is a promising strategy to boost the photocatalytic performance for pollution waters restoration, but it is of great challenge because of the requirement of appropriately staggered energy band alignment and intimate interfacial interaction between semiconductors. Herein, a class of core-shell structured Ag2S–AgIO3 Z-scheme heterostructure photocatalysts are designed and developed. Ag2S is generated by the in-situ ion exchange reaction and anchored on the surface of AgIO3, so the intimate interface between AgIO3 and Ag2S is realized. Integration of AgIO3 and Ag2S extends the ultraviolet absorption of AgIO3 to Vis-NIR region, and also promote the charge separation and migration efficiency, contributing to the enhanced photocatalysis activity for composite catalysts. The optimal Ag2S–AgIO4-4 catalyst exhibits a MO photo-degradation rate constant of 0.298 h−1, which reaches 5.77 and 11.4-folds higher than that of AgIO3 (0.044 h−1) and Ag2S (0.024 h−1). The as-obtained composite catalyst exhibits universally photocatalytic activity in disintegrating diverse industrial pollutants and pharmaceuticals. Particularly, driven by natural sunlight, the Ag2S–AgIO4-4 can effectively decompose MO. A plausible Z-scheme photocatalytic mechanism and reaction pathways of MO degradation over composite catalyst are systemically investigated and proposed.

Embedding CsPbBr3 perovskite quantum dots into mesoporous TiO2 beads as an S-scheme heterojunction for CO2 photoreduction

Heterojunction engineering, especially S-scheme heterojunction, has been recognized as a promising way to explore photocatalysts with boosted charge separation and CO2 photoreduction. Herein, we develop a CsPbBr3@mesoporous TiO2 beads (MTB) S-scheme heterojunction by embedding CsPbBr3 perovskite quantum dots (QDs) into the pores of MTB. The intimate interfacial interaction and staggered band structures promised the S-scheme charge transfer route, as confirmed by X-ray photoelectron spectra (XPS), electron spin resonance (ESR), etc. The 0.15CsPbBr3@MTB (15 wt% of CsPbBr3) hybrid exhibited a remarkable yield of 145.28 μmol g−1h−1 for CO2 photoreduction under simulated sunlight irradiation, which was 4.64 and 3.49-fold enhancement than the pristine MTB and CsPbBr3, respectively. This study provides useful guide towards the design of perovskite-based heterojunctions for photocatalytic applications.

NiO-TiO2 p-n Heterojunction for Solar Hydrogen Generation

Photocatalytic water splitting for hydrogen production has been widely recognized as a promising strategy for relieving the pressure from energy crisis and environmental pollution. However, current efficiency for photocatalytic hydrogen generation has been limited due to a low separation of photogenerated electrons and holes. p-n heterojunction with a built-in electric field emerges as an efficient strategy for photocatalyst design to boost hydrogen evolution activities due to a spontaneous charge separation. In this work, we investigated the effect of different preparation methods on photocatalytic hydrogen production over NiO-TiO2 composites. The results demonstrated that a uniform distribution of NiO on a surface of TiO2 with an intimate interfacial interaction was formed by a sol-gel method, while direct calcination tended to form aggregation of NiO, thus leading to an uneven p-n heterojunction structure within a photocatalyst. NiO-TiO2 composites fabricated by different methods showed enhanced hydrogen production (23.5 ± 1.2, 20.4 ± 1.0 and 8.8 ± 0.7 mmolh−1g−1 for S1-20%, S2-20% and S3-10%, respectively) as compared with pristine TiO2 (6.6 ± 0.7 mmolh−1g−1) and NiO (2.1 ± 0.2 mmolh−1g−1). The current work demonstrates a good example to improve photocatalytic hydrogen production by finely designing p-n heterojunction photocatalysts.

A General Strategy toward Metal Sulfide Nanoparticles Confined in a Sulfur-Doped Ti3 C2 Tx MXene 3D Porous Aerogel for Efficient Ambient N2 Electroreduction.

Three-dimensional (3D) porous MXene-based aerogel architectures have attracted great interest for many applications, despite limits in renewable energy conversion owing to the lack of multifunctionality in their components. Herein, a simple and general strategy for constructing a novel functional 3D MXene-based composite heterojunction aerogel (MS@S-MAs) is presented via divalent metal-ion assembly and subsequent thermal sulfidation, and its application in electrochemical nitrogen reduction reaction (NRR) is studied. The as-prepared MS@S-MAs comprises metal sulfide nanoparticles uniformly confined in 3D interconnected conductive S-doped MXene sheets with intimate interfacial interaction. Benefiting from the unique properties and an interfacial interaction, MS@S-MAs exhibit significantly improved NRR catalytic performance and excellent stability because of the higher exposure of electrochemically active sites coupled with easier accessibility, faster mass diffusion, and quicker carrier transport at the interface. Remarkably, CoS@S-MAs show an NH3 yield rate and a Faradaic efficiency of 12.4 µg h-1 mg-1 cat and 27.05% at the lower potential of -0.15V versus a reversible hydrogen electrode in 0.1 m Na2 SO4 solution under ambient conditions, which rivals or exceeds most of the previously reported MXene-based and Co-based catalysts. This work will open avenues to construct 3D MXene-based materials with rich functionalities for energy storage and conversion, catalysis, and other applications.

The covalent Coordination-driven Bi2S3@NH2-MIL-125(Ti)-SH heterojunction with boosting photocatalytic CO2 reduction and dye degradation performance

Herein, the optional and controllable growth of Bi2S3 onto NH2-MIL-125 via covalent conjunction strategy was reported. The experimental results demonstrate that the obtained heterojunction exhibits boosting photocatalytic reduction CO2 and organic dye degradation. The 18-Bi2S3@NH2-MIL-125-SH displays the highest yield of 12.46 μmol g−1h−1 of CO, >13 times that of pure NH2-MIL-125. Meanwhile, the reaction kinetic of 18-Bi2S3@NH2-MIL-125-SH in the degradation of methylene blue is uppermost, which is 160 times than that of the commercial P25. The enhancement of photocatalytic performance could be ascribed to the covalent coordination-driven intimate interfacial interaction in n-scheme heterojunction. Meanwhile, the plausible mechanism was also investigated by UV–vis diffuse reflectance (UV–vis), photoluminescence (PL), electrochemical photocurrent, electron spin resonance (ESR) and electrochemical impedance spectroscopy (EIS).

Interfacial Mo-N-C Bond Endowed Hydrogen Evolution Reaction on MoSe2@N-Doped Carbon Hollow Nanoflowers.

Molybdenum diselenide (MoSe2) has been considered as promising electrocatalysts for catalyzing the hydrogen evolution reaction (HER) due to its narrow band gap and appropriate adsorption free energy. However, its catalytic performance is still impeded by inferior electrical conductivity and insufficient active sites, thus leading to unsatisfactory HER performance. Herein, MoSe2@N-doped carbon (NC) hollow nanoflowers with interfacial Mo-N-C bonds were controllably fabricated through the in situ selenization of the self-polymerized Mo-polydopamine precursor. Benefiting from the unique hollow structure, NC protective layer, and intimate interfacial interaction, the optimal MoSe2@NC displays good HER performance with low overpotentials (175 and 183 mV) and long-term stability (up to 12 h at -10 mA cm-2) in 0.5 M H2SO4 and 1.0 M KOH solutions, respectively. The theoretical results show that Mo-N-C bonds at the interface of MoSe2@NC give rise to relatively low unoccupied eg orbital density of states and ideal H2 adsorption free energy. This work presented here highlights the critical role of interfacial chemical bonds in regulating the electronic structure of nanomaterials and further improving the HER performance.

Nanocomposite catalyst of graphitic carbon nitride and Cu/Fe mixed metal oxide for electrochemical CO2 reduction to CO

To address the challenges of excessive emission of CO2, development of highly efficient electrocatalysts based on earth-abundant metals and non-metals for CO2 reduction is of great importance. Herein, we report a novel g-C3N4/Cu2O-FeO heterogeneous nanocomposite catalyst for electrochemical CO2 reduction to CO, with a maximum Faradaic efficiency of 84.4 % at a low onset overpotential of -0.24 V vs. normal hydrogen electrode (NHE). Moreover, the turnover frequency for CO2 conversion to CO reached 10300 h−1 with a high selectivity of 96.3 % at -1.60 V vs. Ag/AgCl, corresponding to a thermodynamic overpotential of -0.865 V vs. NHE. The excellent CO2 reduction to CO can be attributed to the intimate interfacial interaction between the g-C3N4 and metal oxides (Cu2O-FeO) and the higher electrochemically active surface area. Therefore, this work demonstrates the use of a g-C3N4/mixed metal oxide heterostructure as a novel and efficient nanocomposite for electrocatalytic CO2 reduction in neutral aqueous medium.

Realization of electrolyte interface effect on Bi2Te3 implanted flake-like ZnO thin films for understanding the highly stable PEC water splitting under simulated solar light and visible light

This study aimed to rationally design the novel Bi2Te3 implanted ZnO (Bi2Te3@ZnO) thin films using simultaneous RF and DC magnetron sputtering technique. Herein, we explored the electrolyte interface effect (0.1 M of KOH, KCl, Na2SO3 and Na2SO4) on ZnO and Bi2Te3@ZnO towards highly stable PEC water splitting activity for the first time. Specifically, morphological evolution and electrolyte ion diffusion properties play a crucial role in realizing the prolonged charge carrier lifetime. Moreover, Bi2Te3@ZnO is highlighted with unique nanocone-shaped morphology compared to flake-like ZnO. Also, constructive interfacial interaction was observed between Bi2Te3 and ZnO. As a result, Bi2Te3@ZnO demonstrated superior and highly stable photocurrents in the KOH electrolyte compared to KCl, Na2SO3 and Na2SO4 electrolytes. Precisely, Bi2Te3@ZnO triumphed highly stable photocurrents about 7.93 × 10–4 A cm−2 compared to ZnO (6.02 × 10–4) at +0.4 V under solar light in KOH electrolyte. Accordingly, Bi2Te3@ZnO achieved remarkable photoconversion efficiency (η) about 0.65 %, which is enabled by the strengthened intimate interaction between Bi2Te3 and ZnO. Furthermore, we compared the PEC activity under visible light (UV cut-off solar light). These results highlighted that the photoconversion efficiency difference between Bi2Te3@ZnO and ZnO (about 4 times) under visible light is relatively higher than solar light (1.3 times) in KOH. Thus, we proposed different charge carrier generation mechanisms of Bi2Te3@ZnO under solar and visible light. Therefore, intimate interfacial interaction, surface modification, ion diffusion and photoelectrode-electrolyte interaction are key parameters to enhance the PEC activity. Overall, rational design of the transition metal oxide/thermoelectric material interface using Bi2Te3@ZnO composite paves a new path towards highly stable photoanode during PEC water splitting activity in the KOH electrolyte environment.

In situ one-pot fabrication of MoO3−x clusters modified polymer carbon nitride for enhanced photocatalytic hydrogen evolution

Developing low-cost and high-efficient noble-metal-free cocatalysts has been a challenge to achieve economic hydrogen production. In this work, molybdenum oxides (MoO3−x) were in situ loaded on polymer carbon nitride (PCN) via a simple one-pot impregnation-calcination approach. Different from post-impregnation method, intimate coupling interface between high-dispersed ultra-small MoO3−x nanocrystal and PCN was successfully formed during the in situ growth process. The MoO3−x-PCN-X (X=1, 2, 3, 4) photocatalyst without noble platinum (Pt) finally exhibited enhanced photocatalytic hydrogen performance under visible light irradiation (λ>420 nm), with the highest hydrogen evolution rate of 15.6 µmol/h, which was more than 3 times that of bulk PCN. Detailed structure-performance revealed that such improvement in visible-light hydrogen production activity originated from the intimate interfacial interaction between high-dispersed ultra-small MoO3−x nanocrystal and polymer carbon nitride as well as efficient charge carriers transfer brought by Schottky junction formed.