RESUMEN

Electrocatalytic water splitting produces green and pollution-free hydrogen as a clean energy carrier, which can effectively alleviate energy crisis. In this paper, bimetallic and selenium doped cobalt molybdate (Se-CoMoO4) nanosheets with rough surface are resoundingly prepared. The multihole Se-CoMoO4 nanosheets display ultrathin and rectangular architecture with the dimensions of âˆ¼ 3.5 µm and 700 nm for length and width, respectively. The Se-CoMoO4 electrocatalyst shows remarkable water electrolysis activity and stability. The overpotentials of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are 270 and 63.3 mV at 10 mA cm-2, along with low Tafel slopes of 51.6 and 62.0 mV dec-1. Furthermore, the Se-CoMoO4 couple electrolyzer merely requires a cell voltage of 1.48 V to achieve 10 mA cm-2 current density and presents no apparent attenuation for 30 h. This investigation declares that the hybridization of transition bimetallic oxide with nonmetallic adulteration can afford a tactic for the preparation of bifunctional non-precious metal-based electrocatalysts.

RESUMEN

Highly efficient water electrolytic agents are restricted by the lack of cheap and Earth-abundant catalysts that can manipulate at unharsh conditions and be prepared with a simple procedure. Here, hierarchically vertical and porous MoS2-CoS2heterojunction nanosheet arrays are designed and fabricated. The MoS2-CoS2nanosheets are composed of ultrasmall nanocrytallites with the dimension of ∼62 nm. This special and novel architecture presents synergistic properties to create excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), where high density active sites generated by ultrasmall nanocrytallites with heterostructures, and the vertical and porous structure accelerates electrolyte transport with luxuriant channels while this hierarchically collaborative framework guarantees completely exposed active sites to electrolytes. This electrode shows low overpotentials of 295 and 103 mV at 10 mA cm-2, small Tafel slopes of 70 and 78 mV dec-1, and long stability for OER and HER, respectively. This work indicates that vertical and porous heterojunction nanosheet arrays with hierarchically ultrasmall secondary nanostructures are a promising catalyst for widespread application.

Asunto(s)

Hidrógeno , Molibdeno , Porosidad , Electrodos , Oxígeno

RESUMEN

Optimizing of electrocatalytic hydrogen evolution reaction (HER) activity is still a gigantic challenge for improving catalysts in renewable energy field. In this research, large-scale neoteric three-dimensional (3D) hierarchical MoSe2 hollow sphere arrays with like-Pacific Plate architecture were triumphantly prepared via a facile and reliable approach. The like-Pacific Plate architecture consists of many 3D MoSe2 arrays plates with the dimensions of 10-35 µm, which is assembled by plentiful closely connecting hierarchical MoSe2 hollow spheres with the outer diameter, hierarchically secondary unit size and shell thickness of 450 nm, 25 nm and 10 nm, respectively. The products exhibited remarkable HER performance with small Tafel slope (58.5 mV dec-1), low overpotential (169.8 mV) at 10 mA cm-2, high conductivity and durable stability, which are attribute to the mechanisms (1) 3D hollow framework furnishes large specific surface area, (2) hierarchical structure generates more active sites, (3) like-Pacific Plate architecture facilitates the touch of electrolyte and catalyst, and (4) closely packed arrays expedite the migration of electron. The current work indicates that unique 3D hierarchical hollow sphere arrays with like-Pacific Plate architecture will be a potential candidate for effective electrocatalytic water splitting catalyst material with energy source application.