Domino Effect: Gold Electrocatalyzing Lithium Reduction to Accelerate Nitrogen Fixation.

Green production of NH3 , especially the Li-mediated electrochemical N2 reduction reaction (NRR) in non-aqueous solutions, is attracting research interest. Controversies regarding the NRR mechanism greatly impede its optimization and wide applications. To understand the electrocatalytic process, we treated Au coated carbon fibrous paper (Au/CP) as the model catalyst. In situ XRD confirmed the transformation of lithium intermediates during NRR. Au greatly improved electron transfer kinetics to catalyze metallic Li formation, and accordingly highly accelerated spontaneous NRR. The Faradaic efficiency of NRR on Au/CP reached 34.0 %, and NH3 yield was as high as 50 µg h-1 cm-2 . Our research shows that the key step of Li-mediated non-aqueous NRR is electrocatalytic Li reduction and offers a novel electrocatalyst design method for Li reduction.

An all-inorganic lead halide perovskite-based photocathode for stable water reduction.

Lead halide perovskites (LHPs) have been investigated for photoelectrochemical hydrogen generation from water splitting. However, the harsh requirements in preparing the environment, i.e. isolating water and oxygen, hinder the wide applications of lead halide perovskites. Herein, an all-inorganic perovskite, i.e. a CsPbBr3-based photocathode, has been prepared to generate hydrogen. It is notable that as a valuable trial for a potential large-scale production, the whole preparation process was completed in an open-air environment. The LHP photocathode achieved the highest photocurrent of about 1.2 mA cm-2 at 0 VRHE. And the photocurrent remains around 94% after continuous illumination for 1 h with the Faradaic efficiency of 90%, illustrating a good photoelectrochemical stability. The all-inorganic LHP photocathodes are facile to prepare with a relatively good performance, and can be improved via band engineering and structure optimization, of which large-scale applications can be expected.

Adjusting the Crystallinity of Mesoporous Spinel CoGa2O4 for Efficient Water Oxidation.

Effective and stable electrocatalysts (ECs) are of great importance for the modification of semiconductor (SC) photoanodes, to achieve efficient photoelectrochemical (PEC) water splitting. Herein we demonstrate that the low-crystallinity mesoporous spinel CoGa2O4 oxygen evolution catalyst (OEC), exhibiting excellent bulk electrocatalytic stability and activity for oxygen-evolving reaction (OER), obviously improved water oxidization on a-Fe2O3 photoanode. Low crystallinity not only balances the stability and activity for ECs themselves but facilitates formation of adjustable Schottky junctions between ECs and SCs. Those would contribute to surface state passivation and photogenerated hole extraction, leading to lower onset potential and larger photocurrent. Thus, our finding suggests that low crystallinity could serve as a beneficial feature of ECs to achieve efficient PEC water splitting, owing to its preponderant tendency for the improvement of interface reaction kinetics.