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Novel Porous Boron Nitride Nanosheet with Carbon Doping: Potential Metal-Free Photocatalyst for Visible-Light-Driven Overall Water Splitting
摘要： The band gap of hexagonal boron nitride (h-BN) is far too wide for efficiently utilizing visible light, limiting its application in photocatalysis. The present study employs first principles calculations to demonstrate that the band gap energies of porous h-BN (p-BN) can be tuned by carbon doping to levels appropriate for the absorption of visible-light, and that the conduction band and valence band match well with the potentials of both hydrogen and oxygen evolution reactions. Importantly, a strategy of carbon doping to improve the energy level of valence band maximum is also proposed. Moreover, the carbon-doped p-BN exhibits good separation between photogenerated electrons/holes and structural stability at high temperatures. The DFT results help the design of high-performance two-dimensional photocatalysts that avoid the use of metals.
关键词： metal-free catalysts,photocatalyst,porous boron nitride nanosheets,overall water splitting,band structure engineering
更新于2025-09-23 15:22:29
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Artificial Mn4Ca-cluster with Exchangeable Solvent Molecules Mimicking the Oxygen-Evolving Center in Photosynthesis
摘要： The natural Mn4Ca-cluster in photosystem II serves as a blueprint to develop artificial water-splitting catalysts in artificial photosynthesis. Although significant advances have recently been achieved, it remains great challenges to prepare robust artificial Mn4Ca-cluster to precisely mimic the structure and function of the biological catalyst in the laboratory. Here, we report the isolation and structural characterization of two Mn4CaO4-complexes from polar solvents acetonitrile or N, N-dimethylformamide, which closely mimics the two water molecules on calcium ion, as well as, the oxidation states of the four manganese ions and the main geometric structure of the natural Mn4Ca-cluster. These new artificial Mn4Ca-complexes provide important chemical clues to understand the structure and mechanism of its biological paragon.
关键词： bioinorganic chemistry,photosynthesis,manganese,heterometallic complexes,water splitting
更新于2025-09-23 15:22:29
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Photoelectrochemical water splitting with p-type metal oxide semiconductor photocathodes Youn Jeong Jang[a] and Jae Sung Lee*[a]
摘要： Photoelectrochemical (PEC) water splitting is a promising way to produce clean and sustainable hydrogen fuel. Solar hydrogen production using p-type metal oxide semiconductor photocathodes has not been studied as extensively as n-type metal oxide semiconductor photoanodes and p-type PV-grade non-oxide semiconductor photocathodes. Copper-based oxide photocathodes show relatively good conductivity but suffer from instability in an aqueous solution under illumination. On the other hands, Fe-based metal oxide photocathodes demonstrate more stable PEC performance, but have problems in charge separation and transport. In this mini-review article, we provide an overview of the recent progress in p-type metal oxide-based photocathodes for PEC water reduction. Although these materials are not fully developed up to their potential performance, the involved challenges have been identified and strategies to overcome the limitations have been proposed. Future research in this field should address these issues and challenges in addition to discovery of new materials.
关键词： metal oxides,p-type semiconductors,photoelectrochemical cell,photocathodes,solar water splitting
更新于2025-09-23 15:22:29
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Promotion of Overall Water Splitting Activity Over a Wide pH Range by Interfacial Electrical Effects of Metallic NiCo-nitrides Nanoparticle/NiCo <sub/>2</sub> O <sub/>4</sub> Nanoflake/graphite Fibers
摘要： Many efforts have been made to develop bifunctional electrocatalysts to facilitate overall water splitting. Here, a fibrous bifunctional 3D electrocatalyst is reported for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) with high performance. The remarkable electrochemical performance is attributed of the catalysts to a number of factors: the metallic character of the three components (i.e., Ni3N, CoN, and NiCo2O4); the electronic structure, nanoflake-nanosphere network with abundant electroactive sites, and the electric field effect at the interfaces between different components. The oxide–nitride/graphite fibers have the lowest overpotential requirements of 71 and 183 mV at 10 mA cm?2 for HER and OER in alkaline medium, respectively. These values are comparable to those of commercial Pt/C (20 wt%) and RuO2. The electrodes also show a response to HER and OER in both neutral and acid media. Furthermore, the 3D structure can be highlighted by all-round electrodes for overall water splitting. The calculations on the changes in electrons transfer and the Femi level from oxides to oxides/nitrides reveal that the observed superb electrocatalytic performance can be attributed to the presence of Ni3N and CoN derived from the in situ nitridation of NiCo2O4.
关键词： electrocatalysts,overall water splitting,interfacial electrical effects
更新于2025-09-23 15:22:29
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Transparent Ta3N5 Photoanodes for Efficient Oxygen Evolution toward the Development of Tandem Cells
摘要： Photoelectrochemical water splitting is regarded as a promising approach to the production of hydrogen, and the development of efficient photoelectrodes is one aspect of realizing practical systems. In this work, transparent Ta3N5 photoanodes were fabricated on n-type GaN/sapphire substrates to promote O2 evolution in tandem with a photocathode, to realize overall water splitting. Following the incorporation of an underlying GaN layer, a photocurrent of 6.3 mA cm-2 was achieved at 1.23 V vs. a reversible hydrogen electrode. The transparency of Ta3N5 to wavelengths longer than 600 nm allowed incoming solar light to be transmitted to a CuInSe2 (CIS), which absorbs up to 1100 nm. A stand-alone tandem cell with a serially-connected dual-CIS unit terminated with a Pt/Ni electrode was thus constructed for H2 evolution. This tandem cell exhibited a solar-to-hydrogen energy conversion efficiency greater than 7% at the initial stage of the reaction.
关键词： solar energy conversion,photoelectrochemistry,water splitting,photoelectrochemical tandem cell,(oxy)nitrides
更新于2025-09-23 15:22:29
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Visible-Light-Driven Photocatalytic Z-scheme Overall Water Splitting in La5Ti2AgS5O7-based Powder Suspension System
摘要： La5Ti2CuxAg1-xS5O7 (x=0-1) is a kind of long-wavelength-responsive oxysulfide photocatalysts for hydrogen evolution, and has been demonstrated to enable the Z-scheme water splitting coupling with oxygen evolution photocatalysts (OEP) the particulate sheet. We herein report that among La5Ti2CuxAg1-xS5O7, La5Ti2AgS5O7 was found to have the highest performance on Z-scheme overall water splitting in conjunction with PtOx-WO3 as an OEP, and a triiodide/iodide (I3?/I?) redox couple as a shuttle electron mediator in powder suspension system. Loading Pt/NiS on La5Ti2AgS5O7 benefits the Z-scheme to achieve an apparent quantum yield of 0.12% at 420 nm. The finding in powder suspension system is opposite to the earlier study on photocatalyst sheet configurations in which p-type doping and the formation of a solid solution can effectively enhance the water-splitting activity. This work not only shows a La5Ti2AgS5O7-based Z-scheme water splitting photocatalyst, but also may present a better understanding for the difference between particulate sheet and powder suspension system available in an optimal strategy for water splitting.
关键词： photocatalysis,water splitting,visible light,Z-scheme,oxysulfides
更新于2025-09-23 15:22:29
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Multifunctional monoclinic VO2 nanorod thin films for enhanced energy applications: Photoelectrochemical water splitting and supercapacitor
摘要： Monoclinic VO2 nanorod thin films were deposited on indium?tin-oxide-coated glass substrates using radio-frequency reactive magnetron sputtering at a substrate temperature of 300 °C and various O2 flow rates. The thin films were characterized via standard analysis techniques. The VO2 thin films exhibited a highly crystalline monoclinic phase with an indirect band gap of ~1.73 eV. At optimized O2 flow rate (4 sccm), the thin films was observed nanorod structures, exhibited a remarkable photocurrent of ~0.08 mA cm?2 during photoelectrochemical water splitting in the visible region. Electrochemical performance tests of the nanorod films revealed a specific capacitance of ~486 mF cm?2 at a scan rate of 10 mVs?1. In addition, amperometric I–t curves showed that VO2 thin film electrodes were highly stable during the photo-oxidation process. The nanorod films also exhibited a good specific capacitance of ~120 mF cm?2 after 5000 cycles at a scan rate of 100 mVs?1. The photocurrents during photoelectrochemical water splitting and the specific capacitance of VO2 thin films deposited at O2 flow rates of 2 and 6 sccm were 0.06 and 0.07 mA cm?2 and 398 and 37 mF cm?2, respectively. The films deposited under Ar at 8 sccm and O2 at 4 sccm showed the highest photoelectrochemical water splitting performance and specific capacitance, owing mainly to their nanorod-like morphology.
关键词： Supercapacitor,Partial pressure,Reactive sputtering,Photoelectrochemical water splitting,VO2,Monoclinic
更新于2025-09-23 15:22:29
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Evidencing enhanced charge-transfer with superior Photocatalytic degradation and Photoelectrochemical water splitting in Mg modified few-layered SnS2
摘要： Recently there has been immense interest in the exploration of richly available two-dimensional non-toxic layered material such as tin disulfide (SnS2) for potential employment in energy and environmental needs. In this regard, we report on the synthesis of few-layered Sn1?xMgxS2 nanosheets through a facile one-step hydrothermal route to address all such functions concerning photocatalysis and photoelectrochemical conversion. The crystalline order and structure of processed layered Sn1?xMgxS2 were initially found to exhibit a strong influence on their physicochemical properties. Their optical properties attest the Mg doping in SnS2 to benefit us with enhanced visible-light absorption via red-shift in their absorption edge. In the photoluminescence spectrum the emissions observed along visible and red region signifies the association of Mg related trap states in Sn1?xMgxS2. Next, the photocurrent and electrochemical impedance spectroscopic results revealed the Mg doping to promote the effective charge transfer process (which was beneficial to enhance their photocatalytic activity). Consequently, the layered Sn0.98Mg0.02S2 made photoanodes displayed 1.7 fold higher photocurrent density under simulated solar radiation with respect to their undoped counterpart. Furthermore, the layered Sn0.98Mg0.02S2 nanosheets exhibits enhanced visible light decomposition of organic dye while compared with pristine SnS2 nanosheets. The value of rate constants obtained for the Sn0.98Mg0.02S2 nanosheets was found to be 1.4 times higher than that of pristine SnS2. Finally, the results obtained through the present study projects the huge potential of layered Sn0.98Mg0.02S2 nanosheets for future multifunctional applications.
关键词： SnS2,Magnesium,Nanosheets,Photocatalysis,Few-layered,Photoelectrochemical water splitting
更新于2025-09-23 15:22:29
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Cobalt/Molybdenum Phosphides and Oxides Heterostructures Encapsulated in N-doped Carbon Nanocomposite for Overall Water Splitting in Alkaline Media
摘要： The development of designing and searching inexpensive electrocatalysts with highly activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is significant to enable water splitting as a future renewable energy source. Herein, we synthesis a new CoP(MoP)-CoMoO3 heterostructure coated by N-doped carbon shell (CoP(MoP)-CoMoO3@CN) via thermal decomposing and phosphatizing the CoMoO4?0.9H2O nanowires encapsulated in N-doped carbon. At 10 mA?cm?2, this CoP(MoP)-CoMoO3@CN nanocomposite exhibits superior electrocatalytic activity of low overpotentials of 296 mV for OER and 198 mV for HER in alkaline media. More importantly, we achieve a current density of 10 mA?cm?2 at 1.55 V by using this CoP(MoP)-CoMoO3@CN as both cathode and anode for overall water splitting. This promising performance could be due to the high activity of CoP(MoP)-CoMoO3 and the good conductivity of external mesoporous N-carbon shell, which makes the CoP(MoP)-CoMoO3@CN nanowires as a competitive alternative to noble metal based catalysts for water splitting.
关键词： metal phosphides,overall water splitting,synergistic effects,nanowires,N-doped Carbon
更新于2025-09-23 15:22:29
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Nanostructuring Strategies To Increase the Photoelectrochemical Water Splitting Activity of Silicon Photocathodes
摘要： Photoelectrochemical water splitting is a promising route for sustainable hydrogen production. Herein, we demonstrate a photoelectrode motif that enables a nanostructured large-surface area electrocatalyst without requiring a nanostructured semiconductor surface with the goal of promoting electrocatalysis while minimizing surface recombination. We compare the photoelectrochemical H2 evolution activity of two silicon photocathode nanostructuring strategies: (1) direct nanostructuring of the silicon surface and (2) incorporation of nanostructured zinc oxide to increase the electrocatalyst surface area on planar silicon. We observed that silicon photocathodes that utilized nanostructured ZnO supports outperformed nanostructured silicon electrodes by ～50 mV at open circuit under 1 sun illumination and demonstrated comparable electrocatalytic activity.
关键词： photocathodes,silicon nanowires,hydrogen evolution,molybdenum disulfide,zinc oxide nanowires,photoelectrochemical water splitting
更新于2025-09-23 15:22:29