Tuning Active Metal Atomic Spacing by Filling of Light Atoms and Resulting Reversed Hydrogen Adsorption-Distance Relationship for Efficient Catalysis

Precisely tuning the spacing of the active centers on the atomic scale is of great significance to improve the catalytic activity and deepen the understanding of the catalytic mechanism,but still remains a challenge.Here,we develop a strategy to dilute catalytically active metal interatomic spacing(d_(M-M))with light atoms and discover the unusual adsorption patterns.For example,by elevating the content of boron as interstitial atoms,the atomic spacing of osmium(d_(Os-Os))gradually increases from 2.73 to 2.96?.More importantly,we find that,with the increase in dOs-Os,the hydrogen adsorption-distance relationship is reversed via downshifting d-band states,which breaks the traditional cognition,thereby optimizing the H adsorption and H_2O dissociation on the electrode surface during the catalytic process;this finally leads to a nearly linear increase in hydrogen evolution reaction activity.Namely,the maximum dOs-Os of 2.96?presents the optimal HER activity(8 mV@10 mA cm^(-2))in alkaline media as well as suppressed O adsorption and thus promoted stability.It is believed that this novel atomic-level distance modulation strategy of catalytic sites and the reversed hydrogen adsorption-distance relationship can shew new insights for optimal design of highly efficient catalysts.

Electric field and photoelectrical effect bi-enhanced hydrogen evolution reaction

Molybdenum disulfide （MoS2） is an earth-abundant and low-cost hydrogen evolving electrocatalyst with the potential to replace traditional noble metal catalysts. The catalytic activity can be significantly enhanced after modification due to higher conductivity and enriched active sites. However, the underlying mechanism of the influence of the resistance of electrode material and contact resistance on the hydrogen evolution reaction （HER） process is unclear. Herein, we present a systematic study to understand the relationship between HER performance and electrode conductivity, which is bi-tuned through the electric field and photoelectrical effect. It was found that the onset overpotential consistently decreased with the increase of electrode conductivity. In addition, the reduction of the contact resistance resulted in a quicker electrochemical reaction process than enhancing the conductivity of the MoS2 nanosheet. An onset overpotential of 89 mV was achieved under 60 mW/cm^2 sunlight illumination （0.6 sun） and a simultaneous gate voltage of 3 V. These physical strategies can also be applied to other catalysts, and offer new directions to improve HER catalytic performance of semiconductor materials.

Fabricating ion-conducting channel in SU-8 matrix for highperformance patternable polymer electrolytes

Advances in electrochemical energy storage technologies drive the need for battery safety performance and miniaturization,which calls for the easily processable polymer electrolytes suitable for on-chip microbattery technology.However,the low ionic conductivity of polymer electrolytes and poor-patternable capabilities hinder their application in microdevices.Herein,we modified SU-8,as the matrix material,by poly(ethylene oxide)(PEO)with lithium salts to obtain a patternable lithium-ion polymer electrolyte.Due to the highly amorphous state and more Li-ion transport pathways through blending effect and the increase in number of epoxides,the ionic conductivity of achieved sample is increased by an order of magnitude to 2.9×10^(−4) S·cm^(−1) in comparison with the SU-8 sample at 50°C.The modified SU-8 exhibits good thermal stability(>150°C),mechanical properties(elastic modulus of 1.52 GPa),as well as an electrochemical window of 4.3 V.Half-cell and microdevice were fabricated and tested to verify the possibility of the micro-sized on-chip battery.All of these results demonstrate a promising strategy for the integration of on-chip batteries with microelectronics.