Potential of zero free charge (PZFCs) of Pt(111)/0.1 M HClO 4 interface with adsorbed P-block elements X ad ( X = I, Br, Te, Se and S) of various coverages are investigated using electrochemical reduction of peroxodisulfate (PDS) as the probe reaction, aiming at understanding the mechanism of adatom in regulating the PZFCs of Pt(111)@X ad /0.1 M HClO 4 interface. Experimental observations reveal that increase adatom coverage on Pt(111) results in a monotonic positive shift in the PZFCs with S, Se and Br adatoms. The maximum PZFCs with saturated S ad , Se ad and Br ad are in the range of ca. 0.5–0.53 V RHE , which is positively shifted by ca. 0.14–0.17 V comparing to the PZFC of unmodified Pt(111)/0.1 M HClO 4 interface. In contrast, whereas I and Te adatoms lead to a nonmonotonic change of PZFCs with coverage, characterized by an initial positive shift up to ca. 0.51/0.48 V RHE followed by a sharp drop down to ca. 0.17/0.14 V RHE at higher coverages. The origin for such phenomenon can be well rationalized by the displacement of adsorbed water on Pt(111) by X ad , such displacement induced change of electron spillover from the Pt surface as well as the electronic effect of X ad and Pt.
‘Anode-free’ Li metal batteries offer the highest possible energy density but face low Li coulombic efficiency when operated in carbonate electrolytes. Here we report a performance improvement of anode-free Li metal batteries using p -block tin octoate additive in the carbonate electrolyte. We show that the preferential adsorption of the octoate moiety on the Cu substrate induces the construction of a carbonate-less protective layer, which inhibits the side reactions and contributes to the uniform Li plating. In the mean time, the reduction of Sn 2+ at the initial charging process builds a stable lithophilic layer of Cu 6 Sn 5 alloy and Sn, improving the affinity between the Li and the Cu substrate. Notably, anode-free Li metal pouch cells with tin octoate additive demonstrate good cycling stability with a high coulombic efficiency of ~99.1%. Furthermore, this in situ p -block layer plating strategy is also demonstrated with other types of p -block metal octoate, as well as a Na metal battery system, demonstrating the high level of universality.
The metallic phase MoS 2 (1T-MoS 2 ) supported metal-nanocatalyst is an appealing material system for accelerating the redox kinetics of non-aqueous Li | |O 2 batteries. However, the drawbacks associated with the surface orbital steric effect and the internal electron coupling results in a detrimental effect for the stability of 1T-MoS 2 , especially for the interface charge transfer. This makes it difficult to incorporate guest metal nanoparticles without compromising the 1 T phase support. To circumvent these issues, here we propose a p-block element (In-O) doping strategy to stabilize the 1 T phase MoS 2 by moderating the surface orbital steric effect and strengthening the internal chemical bonding, and thus for the epitaxial Ru nanocatalyst graft on the stabilized 1T-MoS 2 for Li | |O 2 batteries. The experimental and theoretical analyzes indicate that the In-O-MoS 2 @Ru enhances the O 2 dissociation and facilitates the adsorption of LiO 2 intermediates. This effect promotes the growth of weakly crystalline Li 2 O 2 films during oxygen reduction reaction, which can be more easily decomposed during the oxygen evolution reaction, thereby enhancing the bifunctional-catalytic kinetics. When employed at the positive electrode for non-aqueous Li | |O 2 batteries, In-O-MoS 2 @Ru shows an overpotential of 0.37 V and a cycling life of 284 cycles at 200 mA g −1 with a final discharge specific capacity of 1000 mAh g −1 at 25 °C.
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