Search

This work reports the synthesis of CuxSny alloy aerogels for electrochemical CO2 reduction catalysts. An in situ reduction and the subsequent freeze-drying process can successfully give CnxSny aerogels with tuneable Sn contents, and such aerogels are composed of three-dimensional architectures made from inter-connected fine nanoparticles with pores as the channels. Density functional theory (DFT) calculations show that the introduction of Sn in Cu aerogels inhibits H2 evolution reaction (HER) activity, while the accelerated CO desorption on the catalyst surface is found at the same time. The porous structure of aerogel also favors exposing more active sites. Counting these together, with the optimized composition of Cu95Sn5 aerogel, the high selectivity of CO can be achieved with a faradaic efficiency of over 90% in a wide potential range (−0.7 V to −1.0 V vs. RHE). [ABSTRACT FROM AUTHOR]

H2 is promising clean energy and electrochemical hydrogen evolution reaction offers a sustainable route compared with traditional methane steam reforming. In this work, highly porous Co2Ni and Co2Ni/reduced graphene oxide composite aerogels are prepared by a simple in-situ reduction-gelation method in an aqueous solution. The synthesis starts with Co-Ni hydrogel which is prepared by mixing a strong reduction agent NaBH4 with the corresponding metal ions, while graphene oxide is reduced simultaneously in the gelation process. After supercritical drying, composite aerogels composed with interconnected binary Co2Ni nanoparticles network and reduced graphene oxide sheets are obtained. Such optimized composite alloy/reduced graphene oxide aerogels show good hydrogen evolution catalytic activity in alkaline electrolytes, which is highlighted by the low on-set overpotential (143 mV@10 mA/cm2) and small Tafel slope (85 mV/dec). Highlights: 3D-porous Co2Ni/rGO composite aerogel was prepared by an in-situ reduction. rGO increased the surface area and promoted the charge transfer capability. The composite aerogel exhibited good HER catalytic activity. [ABSTRACT FROM AUTHOR]

The addition of appropriate organic acid additives in the sol–gel process not only facilitates the gelation of CeO 2 gel, but also provides a way to control the size of Au nanoparticles in the final Au-CeO 2 aerogel photocatalysts and ultimately affects their performance for CO 2 reduction. [Display omitted] Tuning the size of Au nanoparticles is always an interesting task when constructing Au/semiconductor heterojunctions for surface plasmon resonance-enhanced photocatalysis. In particular, the size of Au nanoparticles in the newly emerging "plasmonic aerogel" photocatalyst concept could approach the size of the semiconductor phase. This work provides an alternative route to realize the size tuning of Au nanoparticles in Au-CeO 2 composite aerogels to some extent, within the framework of the well-established epoxide addition sol–gel method. The size tuning is achieved by exploiting the multi-functionalities of a mixed organic acid additive containing a thiol group in the gelation step. The obtained aerogel photocatalysts are composed of a porous backbone of interconnected CeO 2 nanoparticles and Au nanoparticles, and the size of Au nanoparticles ranges from ∼30 nm to sub-10 nm, while the size of CeO 2 remains at ∼15–10 nm. The surface plasmon resonance peak position and intensity contributed by the Au nanoparticles then vary accordingly. Photocatalytic CO 2 reduction at the gas–solid interface is chosen as a model reaction to study the effect of Au nanoparticle size on the photocatalytic activity of composite aerogel photocatalysts. The addition of Au nanoparticles undoubtedly enhances the overall activity of the CeO 2 aerogel photocatalyst, while the degree of enhancement (in terms of total charge consumption) and product selectivity (CH 4 or CO) are different and correlated with the size of the Au nanoparticles. The best performance can be achieved in a composite in which the Au sizes are the smallest. [ABSTRACT FROM AUTHOR]

We report the synthesis of porous NiCo 2 S 4 and NiCo 2 S 4 -reduced graphene oxide composite aerogel with high surface area (up to 262.4 m 2 /g) and large pore volume (up to 1.44 cm 3 /g). The aerogel is prepared by “DL-Mercaptosuccinic acid accelerated” sol-gel method, which is different from the well-established “nanoparticle condensation” and “metathesis” methods in terms of precursors and reaction mechanism. The fundamental of such method relies on the dual functionality of DL-Mercaptosuccinic acid, which not only initiated the sol-gel transition, but also offered sulfur source for metal sulfide. The complex interactions between the functional groups (COOH, -SH etc.) in DL-Mercaptosuccinic acid and the metal ions yield robust gel networks. After supercritical drying in ethanol, well crystallized monolithic NiCo 2 S 4 and NiCo 2 S 4 -reduced graphene oxide aerogel can be obtained. High specific capacitance of 1268 F/g at 1 A/g and high energy density of 13.4 Wh/kg at the power density of 0.75 kW/kg can be achieved when the aerogel is used as supercapacitor electrode. The low on-set overpotential of 250 mV and small Tafel slope of 70 mV/dec also confirmed the aerogel is good catalyst for electrochemical oxygen evolution reaction. [ABSTRACT FROM AUTHOR]