Robust Photoelectrochemical Oxygen Evolution with N, Fe–CoS₂ Nanorod Arrays

Abstract

Photoelectrochemical water splitting is a promising approach to enhance the efficiency of water splitting. However, it is still challenging to develop an efficient oxygen evolution reaction (OER) electrocatalyst that can be coupled with light due to inefficient light utilization. Here, we demonstrate that N, Fe-co-doped CoS 2 (N, Fe−CoS 2 ) nanorod arrays can act as a highly efficient photo-coupled electrochemical OER catalyst. In dark conditions, the N, Fe-doped CoS 2 on selfsupported stainless steel (SS) mesh shows a small OER overpotential (215 mV) at a current density of 10 mA cm −2 , a reduced Tafel slope (43.2 mV dec −1 ), and negligible activity decay after 10 000 cycles. Upon visible−NIR light illumination, the N, Fe-doped anode exhibits superior photoelectrochemical performance because of the enhanced photoresponse, excellent light harvesting ability and promoted interfacial kinetics of charge separation. Our well-designed photoelectrochemical OER electrode can not only serve as a light absorption semiconductor but also the active catalytic sites for the OER reaction; the electrode composed of the single phase can efficiently avoid photocarrier recombination at the grain boundary. This study provides an insight into photoanode synthesis for photoelectrochemical OER and offers guidance on the future electrocatalyst design.

A Ternary Dumbbell Structure with Spatially Separated Catalytic Sites for Photocatalytic Overall Water Splitting

“…[ 32,33 ] Compared with metal‐based molecular cocatalysts, non‐photoresponsive metal oxides, such as RuO 2 and IrO 2 , are alternative oxidation cocatalysts with low resistivity and high corrosion resistance. [ 34–36 ] Therefore, we can expect that the deposition of metal oxides cocatalysts onto the sidewalls of 1D metal sulfide structure can effectively transfer multiple holes from sulfide to oxidation cocatalysts sites, which is indispensable for water oxidation.…”

Porous Cobalt Sulfide Selenium Nanorods for Electrochemical Hydrogen Evolution

“…In Figure 4 c, peaks located at 55.7 and 54.2 eV are attributed to Se 3d 3/2 and Se 3d 5/2 , respectively, close to the previously reported values of Se doped CoS 2 . 53 And the broad peak located at 59.7 eV corresponds to the surface oxidation of the Se edges. 26 High-resolution spectra of S 2p shown in Figure 4 d can be decomposed into three peaks, locating at 162.8 and 163.9 eV, assigned to S 2p 3/2 and S 2p 1/2, respectively, and locating at 168.9 eV, assigned to S surface oxide contamination in Se–CoS 2- x .…”

“…Previous studies have shown that moderate doping can effectively improve the electrochemical catalytic activities, e.g., N, 39−45 P, 46−50 Ni, 51 Fe, 52,53 Al, 54 Se, 55 Mn, 56 and so on. Therein, the performances of selenide products are much better than those of other products (e.g., sulfur), which may be ascribed to the following reasons: performances of electrochemical catalytic devices.…”

“…Previous studies have shown that moderate doping can effectively improve the electrochemical catalytic activities, e.g., N, − P, − Ni, Fe, , Al, Se, Mn, and so on. Therein, the performances of selenide products are much better than those of other products (e.g., sulfur), which may be ascribed to the following reasons: (i) the Se atom has larger electronegativity than the S atom, and the Se atom can substitute the S atom during a high temperature reaction process; (ii) Se (compared to S) forms a new bond with another element, which causes the lattice spacing to change, facilitating electron conduction at the solution interface, and finally improves the catalytic performance.…”

Vertically-Oriented WS2 Nanosheets with a Few Layers and Its Raman Enhancements

“…Considerable attention has been devoted to two-dimensional (2D) materials as promising functional materials, in particular to transition metal dichalcogenides (TMDCs) [ 1 , 2 , 3 , 4 ], due to rapid advances in synthesis, transfer, spectroscopic detection, and manipulation. Since 2D TMDCs have unique physicochemical properties such as high mobility, large surface area, and significant catalytic activities, they can be effectively used for efficient light harvesting, sensitive photo-detection, and catalytic conversion systems [ 5 , 6 , 7 , 8 ]. Among 2D TMDCs, particularly, tungsten disulfide (WS 2 ), with direct optical band gaps of 1.35 and 2.05 eV for bulk and monolayer structure, is of great interest due to its particular semiconducting behavior, intrinsic electrical conductivity, and electrocatalytic property when the number of layers is lower [ 9 , 10 , 11 ].…”