Minglan Dai,Ting Zhang,Juan Huang,Xiaomin Lang,Qing Li,Jian Zou,Chunmei Li,Jianfeng Tang,Hua Lin
Building p-p heterojunctions with Fermi level difference, due to the motion of energy levels, band bending, and internal electric field generation, can effectively improve the electronic structure of the interface, enrich the active sites of heterojunctions, and promote the adsorption of reaction intermediates, which is an effective approach to constructing high-performance electrocatalysts . In this study, a Co 3 O 4 /MoS 2 p-p heterojunction catalyst with nano-particle/nano-flower structure was designed, inducing charge transfer from Co 3 O 4 to MoS 2 , thereby increasing the negative charge of MoS 2 , improving *H adsorption through electrostatic interaction , enhancing electrocatalytic kinetics, and reducing reaction overpotential. The catalytic performance of MoS 2 for hydrogen evolution reaction was effectively enhanced. In 1 M KOH solution, the current density was 10 mA cm −2 , and the overpotential was 156 mV, with good stability after 40 h of operation. This work provides a new direction for the design of p-p heterojunction electrocatalysts and offers more choices for promoting the development of high-performance non-noble metal catalysts.
Huanhuan Sun,Hongyan Yu,Boyang Han,Junjie Ma,Rensheng Wang,Yanping Song
Pressure-induced surface-enhanced Raman spectroscopy (PI-SERS) is among the foremost achievements of high-pressure fields, benefiting from the advantage that pressure-modulated interactions between substrates and molecules overcome the weakness of individual substrates or molecules. However, the pressure corresponding to PI-SERS enhancement is currently still at a low-pressure stage within 8 GPa. Therefore, how to realize PI-SERS enhancement under higher or ultrahigh pressure remains a huge challenge. Here, we applied few-layer WS2 (FL-WS2) nanosheets as PI-SERS substrates and selected 4-mercaptobenzoic acid (4-MBA) molecules with a big energy gap as probes to explore PI-SERS enhancement in more depth. The experimental results indicate that the PI-SERS signals increase gradually as pressure increases and reaches a maximum at 18 GPa, which has set a pressure record for the PI-SERS field so far. Different from the C exciton resonance-induced SERS intensities at ambient conditions, the charge-transfer transition between FL-WS2 and 4-MBA is strengthened via the pressure-induced increase in the band gap of FL-WS2 and decrease in the highest-occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energy gap of 4-MBA, thus enhancing PI-SERS signals accordingly. Therefore, this strategy will be beneficial for practical applications in the field of optoelectronics and for the design of other PI-SERS sensors for trace detection in complex and extreme environments.
Dual emission quantum dots (QDs) have attracted considerable interest as a novel phosphor for constructing ratiometric optical thermometry because of its self-referencing capability. In this work, the exploration of codoped Zn–In–S QDs with dual emissions at ≈512 and ≈612 nm from intrinsic Cu and Mn dopants for ratiometric temperature sensing is reported. It is found that the dopant emissions can be tailored by adjusting the Mn-to-Cu concentration ratios, enabling the dual emissions in a tunable manner. The energy difference between the conduction band of the host and Cu dopant states is considered as the key for the occurrence of Mn ion emission. The as-constructed QD ratiometric temperature sensor exhibits a totally robust stability with a fluctuation of ≈ I Cu / I tot versus times lower than 1% and almost no hysteresis in cycles over a broad window of 100–320 K. This discovery represents that the present cadmium-free, intrinsic dual-emitting codoped QDs can open a new door for the synthesis of novel QDs with stable dual emissions, which poise them well for challenging applications in optical nanothermometry.
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