Synthesis of Multi-Functional Graphene Monolayers via Bipolar Electrochemistry.

Graphene has gained substantial research interest in many fields due to its remarkable properties among many other two-dimensional materials. In this study, we propose a wireless electrochemical approach, bipolar electrochemistry, for the precise modification of single layers of graphene at predefined locations, such as distinct edges or corners, with a variety of metals or polymers, thus enabling the elaboration of multi-functional monolayer graphene sheets. We illustrate the concept e. g. by depositing multiple metals, or platinum and a catalyst-containing porous polymer on the same graphene sheet, but at separate corners. This configuration allows activating chemiluminescence on the polymer spot, and simultaneously generates the driving force for autonomous motion on the Pt side through the catalytic decomposition of hydrogen peroxide into oxygen bubbles. This integration of different chemical features on the same object, exemplified by these proof-of-principle experiments, enhances the functionality of two-dimensional materials, paving the way for the use of these hybrid materials for a variety of applications, ranging from sensing and catalysis to targeted delivery.

Spatial Precision Tailoring the Catalytic Activity of Graphene Monolayers for Designing Janus Swimmers.

Graphene monolayers have interesting applications in many fields due to their intrinsic physicochemical properties, especially when they can be postmodified with high precision. Herein, we describe the highly site-selective functionalization of freestanding graphene monolayers with platinum (Pt) clusters by bipolar electrochemistry. The deposition of such metal spots leads to catalytically active hybrid two-dimensional (2D) nanomaterials. Their catalytic functionality is illustrated by the spatially controlled decomposition of hydrogen peroxide, inducing motion at the water/air interface due to oxygen bubble evolution. A series of such 2D Janus structures with Pt deposition at predefined positions (corners and edges) is studied with respect to the generation of autonomous motion. The type and speed of motion can be fine-tuned by controlling the deposition time and location of the Pt clusters. These proof-of-principle experiments indicate that this type of hybrid 2D object opens up interesting perspectives in terms of applications, such as environmental detection or remediation.

Two dimensional Ni2P/CdS photocatalyst for boosting hydrogen production under visible light irradiation.

Two-dimensional (2D) semiconductor materials have attracted considerable attention in the field of photocatalysis due to the high interfacial charge separation efficiency and abundant surface active sites. Herein, we have fabricated 2D/2D sheets of Ni2P/CdS heterostructure for photocatalytic H2 evolution. The microscopic and photocatalytic activity results suggested that Ni2P nanosheets were coupled with snowflake CdS. The optimal hydrogen production rate reached 58.33 mmol h-1 g-1 (QE = 34.38%, λ = 420 nm) over 5 wt% Ni2P, which is equivalent to that of 1 wt% Pt/CdS. Compared with pure CdS, Ni2P/CdS presented lower fluorescence intensity and stronger photocurrent density, which demonstrated that the 2D/2D Ni2P/CdS heterojunction photocatalyst significantly improved the separation efficiency of photogenerated electrons and holes. The excellent performance of Ni2P/CdS clearly indicated that Ni2P was an excellent cocatalyst and could provide abundant active sites for hydrogen evolution.