Single-atom-catalyst with abundant Co-S4 sites for use as a counter electrode in photovoltaics

Surface Engineered Single-atom Systems for Energy Conversion

Single-atom catalysts (SACs) are demonstrated to show exceptional reactivity and selectivity in catalytic reactions by effectively utilizing metal species, making them a favorable choice among the different active materials for energy conversion. However, SACs are still in the early stages of energy conversion, and problems like agglomeration and low energy conversion efficiency are hampering their practical applications. Substantial research focus on support modifications, which are vital for SAC reactivity and stability due to the intimate relationship between metal atoms and support. In this review, a category of supports and a variety of surface engineering strategies employed in SA systems are summarized, including surface site engineering (heteroatom doping, vacancy introducing, surface groups grafting, and coordination tunning) and surface structure engineering (size/morphology control, cocatalyst deposition, facet engineering, and crystallinity control). Also, the merits of support surface engineering in single-atom systems are systematically introduced. Highlights are the comprehensive summary and discussions on the utilization of surface-engineered SACs in diversified energy conversion applications including photocatalysis, electrocatalysis, thermocatalysis, and energy conversion devices. At the end of this review, the potential and obstacles of using surface-engineered SACs in the field of energy conversion are discussed. This review aims to guide the rational design and manipulation of SACs for target-specific applications by capitalizing on the characteristic benefits of support surface engineering.

Ultralong NiSe nanowire anchored on graphene nanosheets for enhanced electrocatalytic performance of triiodide reduction

Like their higher-dimensional counterparts, nanowire structures possess desirable features for electrocatalysis applications. In this study, ultralong NiSe nanowires (of diameters 50-150 nm and length 20 μm) were successfully anchored onto graphene nanosheets (NiSe NW/RGO). The NiSe nanowires were coated with a thick (∼10 nm) disordered surface replete with active sites. Benefiting from the fast charge-transfer channels and plentiful electroactive sites on the NiSe nanowires, in synergy with the high electroactive surface and electrical conductivity of the graphene nanosheets, the optimized NiSe NW/RGO exhibited a remarkably higher electrocatalytic activity than NiSe nanowires and typical Pt counter-electrodes (CEs). NiSe NW/RGO also exhibited the low charge-transfer resistance of 1.64 Ω cm² and delivered a higher power conversion efficiency (PCE = 7.99%) than Pt CEs (PCE = 7.76%).