RESUMEN
Converting solar energy into fuels is pursued as an attractive route to reduce dependence on fossil fuel. In this context, photothermal catalysis is a very promising approach through converting photons into heat to drive catalytic reactions. There are mainly three key factors that govern the photothermal catalysis performance: maximized solar absorption, minimized thermal emission and excellent catalytic property of catalyst. However, the previous research has focused on improving solar absorption and catalytic performance of catalyst, largely neglected the optimization of thermal emission. Here, we demonstrate an optically selective catalyst based Ti3C2Tx Janus design, that enables minimized thermal emission, maximized solar absorption and good catalytic activity simultaneously, thereby achieving excellent photothermal catalytic performance. When applied to Sabatier reaction and reverse water-gas shift (RWGS) as demonstrations, we obtain an approximately 300% increase in catalytic yield through reducing the thermal emission of catalyst by ~70% under the same irradiation intensity. It is worth noting that the CO2 methanation yield reaches 3317.2 mmol gRu-1 h-1 at light power of 2 W cm-2, setting a performance record among catalysts without active supports. We expect that this design opens up a new pathway for the development of high-performance photothermal catalysts.
RESUMEN
Developing a bifunctional electrocatalyst with remarkable performance viable for overall water splitting is increasingly essential for industrial-scale renewable energy conversion. However, the current electrocatalyst still requires a large cell voltage to drive water splitting due to the unsuitable adsorption/desorption capacity of reaction intermediates, which seriously hinders the practical application of water splitting. Herein, a unique SiOx/Ru nanosheet (NS) material was proposed as a high-performance electrocatalyst for overall water splitting. The SiOx/Ru NSs show superior performance in the hydrogen evolution reaction with a low overpotential of 23 mV (@ 10 mA cm-2) and excellent stability for nearly 200 h (@ 10 mA cm-2) in 1 M KOH. By means of the introduction of SiOx, it is beneficial for balancing the local charge density of the surrounding Ru sites. The suitable electronic coupling between the d-band electrons of Ru and the adsorbed species effectively balances the adsorption and desorption of reaction intermediates on the surface. As a result, the catalyst also exhibits overall water splitting activity with a cell voltage of only 1.496 V to reach the current density of 10 mA cm-2. The present work opens up a new strategy for designing high-performance electrocatalysts for water splitting.
RESUMEN
The practical application of high-energy lithium-sulfur battery is plagued with two deadly obstacles. One is the "shuttle effect" originated from the sulfur cathode, and the other is the low Coulombic efficiency and security issues arising from the lithium metal anode. In addressing these issues, we propose a novel silicon-sulfurized poly(acrylonitrile) full battery. In this lithium metal-free system, the Li source is pre-loaded in the cathode, using a nitrogen evolution reaction (NER) to implant Li+ into the silicon/carbon anode. Sulfurized poly(acrylonitrile) based on a solid-solid conversion mechanism can fundamentally circumvent the "shuttle effect". Meanwhile, the silicon/carbon anode can achieve more efficient utilization and higher security when compared with the Li metal anode. The full cell used in this technology can deliver a capacity of 1169.3 mAh g-1, and it can be stabilized over 100 cycles, implying its excellent electrochemical stability. Furthermore, the practical pouch cell with a high sulfur loading of 4.2 mg cm-2 can achieve a high specific energy of 513.2 Wh kg-1. The mechanism of the NER in cathode has also been investigated and analyzed by in situ methods. Notably, this battery design completely conforms to the current battery production technology because of the degassing of gasbag, resulting in a low manufacturing cost. This work will open the avenue to develop a lithium metal-free battery using the NER.
RESUMEN
Developing a high-rate Li metal anode with superior reversibility is a prerequisite for fast-charging Li metal batteries. However, the build-up of large concentration gradients under high current density leads to inhomogeneous Li deposition and unstable passivation layers of Li metal, resulting in lower Coulombic efficiency. Here we report a concentrated dual-salts LiFSI-LiNO3/DOL electrolyte to improve the high-rate performance of Li metal anode. Sufficient Li salts help passivate the fresh Li deposition quickly. Further, DOL contributes to the formation of flexible organic layers that can accommodate the rapid volume change of Li metal upon cycling. Li metal in the electrolyte remains stable over 240 cycles with the average Coulombic efficiency of 99.14% under a high current density of 8.0 mA cm-2.