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A fuel cell involving CO 2 /H 2 is an appealing energy system to convert CO 2 into synthetic fuels as well as to generate electricity using only waste heat. However, overcoming the inherent activation barrier of CO 2 to improve the CO 2 conversion rate in CO 2 /H 2 fuel cell is still challenging. Herein, we report a synergistic electron-donor and proton-repulsion group composed of Pt-N 3 -S-C sites to simultaneously modulate the electronic structure and CO 2 -protonation ability of Ru nanoclusters (Ru NC) in Ru NC /Pt-N 3 -S-C catalyst. Experiments combined with theoretical calculations indicate that Pt-N 3 -S sites not only function as electron donors to Ru nanoclusters to cooperatively induce the orbital hybridization of Ru 3d and the antibonding orbitals of CO 2 , affording the dissociation of C O bonds in CO 2 , but also as electronic structure "modulator" to create new active sites on the surface of Ru NC to effectively activate molecular CO 2. More importantly, an internal polarization field between Pt-N 3 -S-C and Ru NC additionally makes single atom Pt sites repel protons while Ru atoms serve as proton capturers via hydrogen spillover effect, resulting in accelerated protonation of CO 2. Consequently, the catalyst exhibits highly improved catalytic activities for CO 2 reduction with a conversion rate of 559.1 μmol g cat −1 h−1. This approach helps with fine tuning the electronic structures and catalytic CO 2 protonation ability of catalysts for thermal-coupled electrocatalysis. [Display omitted] • A CO 2 /H 2 fuel cell to reduce CO 2 and generate electricity was developed. • Pt-N 3 -S sites can modulate the electronic structure and CO 2 -protonation ability of Ru. • The featured catalysts exhibited excellent catalytic performance for CO 2 reduction. • The catalytic mechanism of catalyst was investigated and revealed in depth. [ABSTRACT FROM AUTHOR]

Abstract Energy consumption continues to rise as society develops worldwide. Meanwhile, a lot of energy is wasted in the form of heat from various devices and systems. Here we report a new power generator, which works based on a difference in H+-ion concentration in a fuel cell structure and produces electricity by harvesting waste heat. The device works via the following three successive processes: H 2 is oxidized at anode to H+ ions, the H+ ions then penetrate through a phosphoric acid-treated polybenzimidazole (PBI-PA) membrane and finally the H+ ions get reduced to H 2 at cathode with electrons coming through external circuit from the anode. This system generates electricity at a current density of 21 mA cm−2 and a power density of 1.03 mW cm−2 at 170 °C. The cell's thermoelectric conversion efficiency at 170 °C is 13.72%, which is higher than typical values reported for many common thermoelectric materials in low temperature regimes. This innovative approach may allow for efficient generation of electricity from waste heat. Graphical abstract fx1 Highlights • A new power generator based on fuel cell structure, H+-ion concentration difference, and waste heat is reported. • The cell takes H 2 at anode and ultimately releases it at cathode, with no overall consumption, except heat while producing electricity. • A high current density of 21 mA cm−2 and a power density of 1.03 mW cm−2 at 170 °C can be obtained. • Thermoelectric conversion efficiency of 13.72% at 170 °C and 3.38% at 50 °C can be achieved by the cell. • The thermoelectric conversion efficiency of the cell is much higher than those of thermoelectric materials-based cells. [ABSTRACT FROM AUTHOR]

Abstract Potassium-ion batteries (PIBs) have been receiving a great deal of attention owing to abundant and cost-effective potassium resources. However, the key issue is to explore suitable electrode materials for accommodating the large size K-ions reversibly. In this report, K 1.06 Mn 8 O 16 /CNT hybrids are systematically studied for the first time as bifunctional PIBs-electrodes, in which Mn-ions play as the redox center. As the cathode, it exhibits excellent electrochemical kinetics and reversibility, as well as highly structure stability. The cathode displays an unprecedented capacity of 309.4 mA h g−1 at 20 mA g−1 with the energy density of 733.3 Wh kg−1 and outstanding rate performance (187.1 mA h g−1 at 500 mA g−1). In addition, the high capacity of 636.6 mA h g−1 at 20 mA g−1, ultra-long cycling lifespan over 500 cycles and remarkable rate capability can also be acquired when the material was tested as the anode. The extraordinary electrochemical properties are ascribed to the well-developed conductive network and robust microstructure stability. Meanwhile, the symmetrical K-ions full cell exhibits high discharge capacity of 241.0 mA h g−1 at 100 mA g−1. This work reveals the K-ions storage mechanism in cryptomelane bifunctional electrodes in depth and the fundamental understanding help us open up a new direction for PIBs. Graphical abstract fx1 Highlights • K 1.06 Mn 8 O 16 /CNT nanohybrid was employed as bifunctional PIBs-electrodes for the first time. • The bifunctional electrodes exhibit excellent electrochemical performances benifited its unique 3D network architecture. • The K-ions storage mechanism for cathode is studied in depth. • The symmetrical K-ions full cell with high discharge capacity was confirmed based on bifunctional electrodes. [ABSTRACT FROM AUTHOR]