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Dual Function of Graphene Oxide for Assisted Exfoliation of Black Phosphorus and Electron Shuttle in Promoting Visible and Near-Infrared Photocatalytic H2 Evolution
摘要： The search for suitable photocatalysts with broadband absorption in visible and near-infrared (NIR) region is recognized as one of the most challenging issues on solar energy utilization. Black phosphorous (BP) is demonstrated as an effective visible and NIR activated material in solar energy conversion. However, traditional liquid exfoliation yield is low and the rigid structure and insoluble properties of pristine BP hinder its high-yield of hybridization. Herein, a new and stable noble-metal-free ternary photocatalyst molybdenum disulfide (MoS2)-BP/graphene oxide (GO) was constructed for splitting water to H2, showing dual functions of GO in synthetic and photocatalytic processes. Under visible-NIR light irradiation, the H2 evolution rates of MoS2-BP/GO was enhanced to 3.47 μmol h-1. Rapid electron injection efficiency from excited BP to GO and to MoS2 was confirmed by femtosecond transient absorption spectroscopy. This study provides new insight into the design of nanomaterials, and offers a noble-metal-free protocol with noble-metal-free.
关键词： visible and NIR,hydrogen evolution,graphene oxide,black phosphorous,noble-metal-free
更新于2025-11-19 16:51:07
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Free-standing black phosphorus thin films for flexible quasi-solid-state micro-supercapacitors with high volumetric power and energy density
摘要： Micro-supercapacitors (micro-SCs) are significant micro-scale power sources and energy storage components for miniaturized electronic and flexible devices, where electrodes play the key role in determining their electrochemical performance. The efficient intercalation of ions between the stacking layers of 2D layered materials (2DLM) makes them great candidates as thin film electrodes in micro-SCs, where one can achieve much enhanced volumetric capacitance. However, a great challenge is to develop a high-yield production method for high quality 2DLM thin film electrodes. In this work, we have successfully reported a scalable fabrication process for free-standing black phosphorous (BP) thin films, derived from the high quality few-layer BP nanoflakes via a modified electrochemical exfoliation route, for flexible quasi-solid-state micro-SCs (QMSCs). The as-fabricated QMSCs exhibit an excellent stable electrochemical performance at a high scan rate up to 100 V s-1. More importantly, our QMSC device can not only achieve an outstanding energy density of 3.63 mW h cm-3, a remarkable power density of 10.1 W cm-3 and a superior cycle span (94.3% capacity retention even after 50000 cycles), but also deliver the excellent mechanical flexibility is demonstrated by 91.3% capacity retention after 500 mechanical bending cycles. More interesting, to meet the energy density and power density needs for various practical applications, multiple QMSCs can be successfully integrated in parallel or in series, which is demonstrated by lighting up of the red light emitting diode (LED). The BP-based QMSCs can be patterned on a single substrate with flexible photodetectors based the same BP thin film to form a self-powered optoelectronic system.
关键词： thin film,black phosphorous,2D layered materials,micro-supercapacitors,energy storage
更新于2025-09-23 15:22:29
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Nonlinear optical response of a two-dimensional semi-Dirac system in terahertz regime
摘要： We demonstrate a strong nonlinear optical response in a two-dimensional semi-Dirac system in the terahertz regime. By applying the Boltzmann transport theory for the intra-band process and a quantum mechanics method for the inter-band process, we obtained the three-photon current response. It is found that both the intra- and inter-band excitations make significant contributions to the nonlinear response. The third order conductivities (TOCs) σyy(3) are about two magnitudes higher than that of σxx(3). Interestingly, for the inter-band TOCs, there is a sign change when the chemical potential varies across the saddle point in the conduction band in kx direction (that is parabolic), due to the competition between the two opposite nonlinear current contributed by the electrons at states k > kD and k < kD, respectively. Finally, we show that the nonlinear response in terahertz regime is significant at experimentally accessible field strengths. Our results suggest that this system could be of potential applications in photonic device for frequency up-conversion.
关键词： black phosphorous,semi-Dirac system,nonlinear optical response,Boltzmann transport theory
更新于2025-09-23 15:22:29
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Black phosphorus quantum dots are useful oxidase mimics for colorimetric determination of biothiols
摘要： Black phosphorus quantum dots (BP QDs) with small size are synthesized using an easy to operate thermal method. It was found that BP QDs possess oxidase-mimicking activity. They can catalyze the oxidation of the substrate 3,3′,5,5′-tetramethylbenzidine to produce a blue-colored product even in the absence of hydrogen peroxide. Active oxygen species are proved to be involved in the reaction through the experiments of radical scavenging and electron spin resonance. Biothiols including reduced glutathione and cysteine inactivate the oxidase-mimicking activity of BP QDs, concomitant to the fading of the blue solution. This provides the base for a colorimetric method for the determination of glutathione and cysteine. The decreased absorbance at 652 nm displays linear response to the concentrations of glutathione ranging from 0.1 to 5.0 μmol L?1, and cysteine from 0.1 to 10.0 μmol L?1. The detection limits are 0.02 μmol L?1 and 0.03 μmol L?1 for glutathione and cysteine, respectively. Successive determinations of 1.0 μmol L?1 glutathione and 5.0 μmol L?1 cysteine solution give relative standard deviations of 0.8% and 1.7% (n = 11), respectively. As a preliminary application, the practicability of the method was evaluated by the determination of glutathione in pharmaceutical preparations. This work not only discovers a useful oxidase mimics but also sets up a reliable platform based on BP QDs in colorimetric detection.
关键词： Cysteine,Pharmaceutical,Nanoprobe,Reactive oxygen species,Black phosphorous quantum dots,Oxidase-mimicking activity,Glutathione,Biothiols,Colorimetric method
更新于2025-09-23 15:19:57
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Van der Waals broken-gap p-n heterojunction tunnel diode based on black phosphorus and rhenium disulfide
摘要： The broken-gap type-III van der Waals (vdW) heterojunction is of particular interest as there is no overlap between the energy bands of its two stacked materials. Despite several studies on straddling-gap (type-I) and staggered-gap (type-II) vdW heterojunctions, a comprehensive understanding of the current-transport and optoelectronic effects in a type-III broken-gap heterojunction remains elusive. Here, we report gate-tunable current rectifying characteristics in a black phosphorus (BP)/rhenium disulfide (ReS2) broken-gap p-n heterojunction diode. Current-transport in this heterojunction was modeled by using the Simmons approximation through direct tunneling and Fowler?Nordheim tunneling in low- and higher-bias regimes, respectively. We showed that a p-n diode based on a type-III heterojunction is mainly governed by tunneling-mediated transport, but that transport in a type-I p-n heterojunction is dominated by majority carrier diffusion in the higher-bias regime. Upon illumination with a 532-nm-wavelength laser, the BP/ReS2 broken-gap p-n heterojunction showed a photo responsivity of 8 mA/W at a laser power as high as 100 μW and photovoltaic energy conversion with an external peak quantum efficiency of 0.3%. Finally, we demonstrated a binary inverter consisting of BP p-channel and ReS2 n-channel thin film transistors for logic applications.
关键词： Rhenium disulfide,photovoltaics,quantum tunneling,broken-gap heterojunction,logic circuitry,Black phosphorous
更新于2025-09-19 17:15:36
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Bandgap Renormalization, Carrier Multiplication and Stark Broadening in Photoexcited Black Phosphorous
摘要： We investigate black phosphorous by time and angle resolved photoelectron spectroscopy. The electrons excited by 1.57 eV photons, relax down to conduction band minimum within 1 ps. Despite the low bandgap value, no relevant amount of carrier multiplication could be detected at excitation density 3 ? 6 × 1019 cm?3. In the thermalized state, the bandgap renormalization is negligible up to a photoexcitation density that fills the conduction band by 150 meV. Astonishingly, a Stark broadening of the valence band takes place at an early delay time. We argue that electrons and holes with high excess energy lead to inhomogeneous screening of near surface fields. As a consequence the chemical potential is no longer pinned in a narrow impurity band.
关键词： Stark,ARPES,Ultrafast,Black Phosphorous,Band-Gap-Renormalization
更新于2025-09-04 15:30:14