With a proper band gap of ∼2.4 eV for solar light absorption and suitable valence band edge position for oxygen evolution, scheelite-monoclinic bismuth vanadate (BiVO 4 ) has become one of the most attractive photocatalysts for efficient visible-light-driven photoelectrochemical (PEC) water splitting. Several studies have indicated that surface modification of BiVO 4 with a cocatalyst such as NiFe layered double hydroxide (LDH) can significantly increase the PEC water splitting performance of the catalyst. Herein, we experimentally investigated the charge transfer dynamics and charge carrier recombination processes by scanning electrochemical microscopy (SECM) with the feedback mode on the surface of BiVO 4 and BiVO 4 /NiFe-LDH as model samples. The ratio of rate constants for photogenerated hole (k h+ 0 ) to electron (k e− 0 ) via the photocatalyst of BiVO 4 /NiFe-LDH reacting with the redox couple is found to be five times larger than that of BiVO 4 under illumination. In this case, the ratio of the rate constants k h+ 0 /k e− 0 stands for the interfacial charge recombination process. This implies the cocatalyst NiFe-LDH suppresses the electron back transfer greatly and finally reduces the surface recombination. Control experiments with cocatalysts CoPi and RuO x onto BiVO 4 further verify this conclusion. Therefore, the SECM characterization allows us to make an overall analysis on the function of cocatalysts in the PEC water splitting system.

Electrochemical reduction of carbon dioxide (CO2RR) to methane has achieved impressive Faradaic efficiencies of over 40% with copper‐based catalysts including Cu2O, copper‐silver alloys and others. Although copper‐based catalysts work effectively in the CO2RR, they suffer from a major disadvantage: low selectivity of desired products due to the difficulty of regulating the intermediate coverage on the catalyst surface. Here, this work presents new SnCuxO2+x nanocluster electrocatalysts encapsulated in purely siliceous MFI zeolites (coded as SnCuxO2+x@MFI) for a high‐efficient CO2RR. This allows the formation of *CO intermediates in the channels of zeolites, which further undergoes a multi‐step protonation process to generate methane, a very attractive feature for Li‐CO2 batteries that use the CO2RR catalyst as the cathode. The obtained SnCu1.5O3.5@MFI catalyst possesses a desired catalytic performance with the Faradaic efficiency of CO2 reduction to methane at 66.6 ± 3.2% in a 0.1 m KHCO3 electrolyte. Using the SnCu1.5O3.5@MFI as a cathode within a Li‐CO2 battery, this work achieves a full discharge specific capacity of 23 000 mAh g−1 at a cut‐off voltage of 2.0 V (vs Li+/Li) and an operational life over 100 cycles at 1000 mAh g−1 cutoff specific capacity. This novel confinement catalyst offers a viable pathway to develop efficient CO2RR and Li‐CO2 batteries with attractive properties for practical applications.

Advances in the rational design of semiconductor-electrocatalyst photoelectrode provide robust driving forces for improving energy conversion and quantitative analysis, while a deep understanding of elementary processes remains underwhelming due to...