Enhanced Overall Water Splitting by a Zirconium‐Doped TaON‐Based Photocatalyst

Abstract

Solar-powered one-step-excitation overall water splitting (OWS) using semiconducting materials is a simple means of achieving scalable and sustainable hydrogen production. While tantalum oxynitride (TaON) is one of the few photocatalysts capable of promoting OWS via single-step visible-light excitation, the efficiency of this process remains extremely poor. The present work employed 15 nm amorphous Ta 2 O 5 •3.3 H 2 O nanoparticles as a new precursor together with Zr doping and an optimized nitridation duration to synthesize a TaON-based photocatalyst with reduced particle sizes and low defect densities. Upon loading with Ru/Cr 2 O 3 /IrO 2 cocatalysts, this material exhibited stoichiometric water splitting into hydrogen and oxygen, with an order of magnitude improvement in efficiency. Our findings demonstrate the importance of inventing/ selecting the appropriate synthetic precursor and of defect control for fabricating active OWS photocatalysts.

Operando measurement of electrocatalyst potential on particulate photocatalysts for overall water splitting

“…[1][2][3][4][5][6] Photocatalytic water splitting is one example of solar-energy conversion into hydrogen. [6][7][8] Although much effort has been devoted to it, 6,[9][10][11][12][13] it is difficult to achieve high solar-to-hydrogen energy conversion efficiency due to the complexities of photocatalytic processes.…”

Defect Engineering of Ta3N5 Photoanodes: Enhancing Charge Transport and Photoconversion Efficiencies via Ti Doping

“…[11,12] In addition, foreign atom doping has been extensively investigated and has led to remarkable performance advances. To date, a wide range of dopant elements, including Zr, [13][14][15] Mg, [16,17] Ge, [18] La, [19] Sc, [20] Na, [21,22] K, [21,22] Rb, [21] and Cs, [21] as well as co-doping with some of these elements, [17,19] have been explored. While several mechanisms have been proposed to describe corresponding improvements of the PEC characteristics of doped Ta 3 N 5 , most studies conclude that the primary role of these dopants is to modulate the concentrations and populations of native point defects (v N and Ta 3+ ), as well as the majority O N donor content.…”

Overall Water Splitting by a SrTaO2N-Based Photocatalyst Decorated with an Ir-Promoted Ru-Based Cocatalyst

“…The dual cocatalyst strategy in which both a hydrogen evolution cocatalyst (HEC) and oxygen evolution cocatalyst (OEC) are incorporated into the OWS system has become popularly investigated to promote OWS effectively. 10,13,14 However, the possible HEC candidates are presently limited to certain noble metals. 2 Bimetals and bimetallic oxides may provide enhanced activities compared with monometallic cocatalysts owing to the tunability of physicochemical properties.…”

“…Adsorption of colloidal IrO 2 (denoted as IrO 2(AD) ) before or after the loading of the CrO y /Ru cocatalyst was not effective in enhancing OWS although IrO 2(AD) effectively promoted the reaction on Y 2 Ti 2 O 5 S 2 , 9 BaTaO 2 N, 10 and TaON. 14 Therefore, an indepth understanding of the structures and functions of the CrO y /Ru/IrO 2(MW) cocatalyst is imperative.…”

“…The latter compound likely resulted from surface oxidation of Ru 0 nanoparticles, in agreement with our previous results. 14 On the other hand, the Ir species showed weak signals distributed over the entire SrTaO 2 N(1) particles in STEM-EDS analysis, and their structure was unclear.…”