Adaptive Bifunctional Electrocatalyst of Amorphous CoFe Oxide @ 2D Black Phosphorus for Overall Water Splitting

Abstract

Water electrolysis offers a promising green technology to tackle the global energy and environmental crisis, but its efficiency is greatly limited by the sluggish reaction kinetics of both the cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER). In this work, by growing amorphous multi‐transition‐metal (cobalt and iron) oxide on two‐dimensional (2D) black phosphorus (BP), we develop a bifunctional electrocatalyst (CoFeO@BP), which is able to efficiently catalyze both HER and OER. The overpotentials for the hybrid CoFeO@BP catalyst to reach a current density of 10 mA cm−2 in 1 m KOH are 88 and 266 mV for HER and OER, respectively. Based on a series of ex‐situ and in situ investigations, the excellent catalytic performance of CoFeO@BP is found to result from the adaptive surface structure under reduction and oxidation potentials. CoFeO@BP can be transformed to CoFe phosphide under reduction potential, in situ generating the real active catalyst for HER.

Phosphorized CoNi2S4 Yolk‐Shell Spheres for Highly Efficient Hydrogen Production via Water and Urea Electrolysis

“…[26,31] In view of the distinguished electrocatalytic performance of the as-prepared P-CoNi 2 S 4 catalyst towards both HER and OER, at wo-electrode electrolyzer was fabricated with P-CoNi 2 S 4 as both the cathodic and anodic catalysts and 1.0 MK OH solution as the medium. Thep olarization curve for water electrolysis (Figure 4g) indicates the superior overall water splitting performance of the P-CoNi 2 S 4 k P-CoNi 2 S 4 couple, which requires al ow cell voltage of 1.544 Vtoafford acurrent density of 10 mA cm À2 compared to 1.533 Vf or aP t/C k RuO 2 couple using commercial catalysts.M ore importantly,t he advantage of this P-CoNi 2 S 4 k P-CoNi 2 S 4 couple is much more significant at higher current densities.One can see that this low cell voltage of 1.544 Vfor P-CoNi 2 S 4 is comparable or superior to that of the most efficient bifunctional electrocatalysts reported (Table S3), including some recently reported values,s uch as 1.46 Vf or Mo-doped Ni 3 S 2 /Ni x P y hollow nanorods, [53] 1.58 Vf or CoFeO@black phosphorus, [54] 1.59 V for Fe 2 CoPS 3 , [55] and 1.62 Vf or Fe-Ni 2 P@P-doped carbon/ Cu x Sa rrays. [56] Besides,t he chronopotentiometry curves recorded at 10 mA cm À2 (Figure 4h)show that the P-CoNi 2 S 4 catalyst exhibits outstanding overall water splitting durability over 100 h, much better than that of the Pt/C k RuO 2 couple.…”

Graphdiyne@NiOx(OH)y heterostructure for efficient overall water splitting

“…But the high cost, scarcity, and low stability under harsh conditions have hindered their practical applications. In the past few years, scientists have made great efforts to synthesize transition metal-based catalysts, such as sulphides, 6,7 oxides, [8][9][10] phosphides, [11][12][13]54,55 and hydroxides, [14][15][16] for efficient water splitting. However, the practical application was limited by their low conductivity, unsatisfactory activity and stability.…”

A novel CoNi7O8/MnO2 nanocomposite supported on Ni foam as a peroxymonosulfate activator for the highly efficient singlet oxygen mediated removal of methylene blue

“…The peaks at 779.9 and 794.9 eV were attributable to Co 3+ 2p 3/2 and 2p 1/2 , respectively, while those at 781.7 and 796.7 eV were related to Co 2+ 2p 3/2 and 2p 1/2 , respectively. 24 Meanwhile, the other two peaks at 785.4 and 802.5 eV were the shake-up satellite peaks of corresponding Co 2p 3/2 and 2p 1/2 . The ratio of Co 2+ to the overall Co on the catalyst surface was 35.9%.…”