Selectivities of Stepped Cu-M (M = Pt, Ni, Pd, Zn, Ag, Au) Bimetallic Surface Environment for C1 and C2 Pathways.

Copper (Cu) emerges as a highly efficient and cheap catalytic agent for the electrochemical reduction of carbon dioxide (CO2RR), promising a sustainable route toward carbon neutrality. Despite its utility, the Cu catalyst exhibits limitations in terms of product selectivity, highlighting the need for the development of a superior catalyst design. Herein, we present a density functional theory (DFT) investigation into the selectivities of Cu-M (M = Pt, Ni, Pd, Zn, Ag, Au) bimetallic catalysts (BMCs) for the carbon dioxide reduction reaction (CO2RR). The interaction between the metals of Cu-M makes the surface electrons reconstruct so that the d-band center shifts to the Fermi level. In terms of CO2 activation, the Cu-Ni catalyst exhibits superior performance. Additionally, the Cu-Pd catalyst favors the formation of *COH along the reaction pathway, favoring the generation of CH4. Conversely, the Cu-Ni catalyst preferentially produces *CHO, thereby favoring the production of CH3OH. For the Cu-Ag catalyst, the reaction intermediates along the C2 pathway are *CO-*CHO and *COH-*CHO. The Cu-Ni catalyst follows a reaction path that proceeds via *CO-*CO → *CO-*COH → *COH-CHO. On the other hand, the Cu-Pt catalyst exhibits a reaction sequence of *CO-*CO → *CO-*CHO → *OCH-*OCH. This study provides guiding significance for the design of Cu-based bimetallic catalysts aimed at improving the selectivities and efficiency of the CO2RR process.

Pyrochlore-type cobalt and manganese antimonate electrocatalysts with excellent activity and stability for OER in acidic solution.

Developing robust electrocatalysts for the oxygen evolution reaction (OER) in acidic solutions that exhibit both good activity and stability remains a significant challenge. This study focuses on the pyrochlore-type Co2Sb2O7 (CSO) material, which exhibits high electrocatalytic activity in harsh acidic solutions by exposing more Co2+ atoms on the surface. In 0.5 M H2SO4, CSO requires a low overpotential of 288 mV to achieve a current density of 10 mA cm-2, and its high activity can remain for 40 h at a current density of 1 mA cm-2 in acidic solutions. BET measurement and TOF calculation verify that the high activity results from the large number of exposed active sites on the surface, as well as the high activity of each active site. The high stability in acidic solutions is due to the in situ formation of the acid-stable oxide CoSb2O6 on the surface during the OER test. Based on first-principles calculations, the high OER activity arises from the special CoO8 dodecahedra and the intrinsic formation of oxygen and cobalt vacancy complexes, which decrease the charge-transfer energy and improve interfacial electron transfer from the electrolyte to the CSO surface. Our findings provide a promising direction for developing efficient and stable OER electrocatalysts in acidic solutions.

Conformal Shell Amorphization of Nanoporous Ag-Bi for Efficient Formate Generation.

Simultaneous attainments of high conductivity and superior catalysis are major challenges for amorphous electrocatalysts in carbon dioxide electroreduction at high overpotential. In this study, one protocol is first demonstrated to drive the shell amorphization of nanoporous Ag-Bi (a-NPSB) catalyst with the spatially interconnected ligament during the initial stage of CO2ER. This newborn a-NPSB bestows the outstanding catalysis, evidenced by a Faradaic efficiency of 88.4% for formate production at -1.15 V vs RHE, specific current density of 21.2 mA cm-2, and mass specific current density of 321 mA mg-1. The unique catalysis is considered as the collective contribution of the conductive ligament internally and amorphous Bi2O3 shell with about 3.2 nm thickness externally. Simultaneous obtaining of the conductivity of inner metals and catalytic activity of the amorphous shell will pave a new avenue for designing a robust electrode during electrochemical reaction.