Periodically patterned MoS2/TiO2 heterostructures were rationally designed as nonmetal plasmonic photocatalysts for highly efficient hydrogen evolution.

Carbon nitride (g-C 3 N 4 ) materials are electroactivated for oxygen reduction (ORR) and oxygen evolution (OER) reactions when they are supported by conductive carbons. However, the electrocatalytic process on semiconductor-based heterostructures such as carbon-supported g-C 3 N 4 still suffers from a huge energy loss because of poor electron mobility. Here, we demonstrated a concept that the conjugation of g-C 3 N 4 with crystalline carbon can improve the in-plane electron mobility and make interior triazine units more electro-active for ORR and OER. As a result, the Co metal coordinated g-C 3 N 4 with crystalline carbons (Co− C 3 N 4 /C) showed a remarkable electrocatalytic performance toward both ORR and OER. For example, it displayed an onset potential of 0.95 V for ORR and an overpotential of 1.65 V for OER at 10 mA cm −2 , which are comparable and even better than those of benchmark Pt, RuO 2 , and other carbon nitride-based electrocatalysts. As a proof-of-concept application, we employed this catalyst as an air electrode in the rechargeable aluminum-air battery, which showed more rechargeable and practicable than those of Pt/C and RuO 2 catalysts in two-electrode coin battery. The characterization results identified that the good performance of Co−C 3 N 4 /C was primarily attributed to the enhanced in-plane electron mobility by crystalline carbon conjugation and the Co-coordinated g-C 3 N 4 along with nitrogen-doped carbons.

efficient and earth-abundant catalysts have been successfully developed including nitrogen-doped carbon materials that possess promising electrocatalytic performance for ORR and OER. [6][7][8][9][10] However, it remains challenging for nitrogen-doped carbon materials to achieve competitive performance to precious metal catalysts due to low nitrogen concentration.Graphitic carbon nitrides (g-C 3 N 4 ) have shown promising performance to replace nitrogen-doped carbon as a highly efficient catalyst, owing to its ultrahigh nitrogen content (theoretically estimated to be ≈60%) and easily tailored structure. [11][12][13][14][15] It is also well-known that the electrocatalytic performance is determined by catalyst structure and accessibility of active sites. It is of significant importance to maximize the electrochemical surface area to better facilitate the transport of reactants (OH − and O 2 ), and therefore enhance catalytic activity. [16][17][18] For this aim, various methods have been reported in preparation of porous g-C 3 N 4 . Conventionally, rigid templates (SiO 2 , Al 2 O 3 , and ZnO) are used to fabricate porous g-C 3 N 4 , [19,20] which can effectively improve accessibility and catalytic activity of g-C 3 N 4 . However, these rigid template-based synthesis methods are complicated, involving several steps such as template formation, template dispersion, template removal, and catalyst purification. These time-consuming processes increase the fabrication cost and can even damage the g-C 3 N 4 active sites during template removal by the use of strong acidic or basic etching. Addressing these challenges will require facile and strategic developments to synthesize porous g-C 3 N 4 without using templates.Herein, we developed a top-down and template-free strategy for the fabrication of porous g-C 3 N 4 (PCN) by controlled pyrolysis of Co 2+ /melamine networks in O 2 atmosphere. After mixing PCN with graphene oxide (GO) and thermal treating in sulfur atmosphere, CoS x @PCN/rGO catalyst was synthesized. The developed CoS x @PCN/rGO catalyst exhibited outstanding electrocatalytic activity and stability toward both OER and ORR. The CoS x @PCN/rGO also showed long cyclability as an air electrode in a zinc-air battery system, outperforming Pt and other precious metal electrocatalysts. The remarkable electrocatalytic performance of CoS x @PCN/rGO is attributed to the internally accessible nitrogen sites and the facilitated transport of intermediates in the porous structure.A typical synthesis route of PCN is schematically depicted in Figure 1a: First, cobalt(II) nitrate hexahydrate was mixed with Porous carbon nitride (PCN) composites are fabricated using a top-down strategy, followed by additions of graphene and CoS x nanoparticles. This subsequently enhances conductivity and catalytic activity of PCN (abbreviated as CoS x @PCN/rGO) and is achieved by one-step sulfuration of PCN/ graphene oxides (GO) composite materials. As a result, the as-prepared CoS x @PCN/rGO catalysts display excellent activity and stability towa...

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We present a facile way to fabricate phosphorus and aluminum codoped nickel oxide-based nanosheets by using layered double hydroxide (AlNi-LDH) as precursors, which showed an overall water-splitting performance in alkaline solution. The codoping of phosphorus and aluminum into nickel oxide nanosheets leads to an optimum balance among surface chemical state, electrochemically active surface area, and density of active sites. As a result, it can afford a current density of 100 mA cm–2 at the overpotential of 310 mV for oxygen evolution reaction (OER) and a current density of 10 mA cm–2 at the overpotential of 138 mV for hydrogen evolution reaction (HER) in 1 M KOH. When it was used as a bifunctional catalyst in a two-electrode water-splitting device, a potential of 1.56 V was achieved at the current density of 10 mA cm–2.