Nanostructured Metal Phosphide Based Catalysts for Electrochemical Water Splitting: A Review

Abstract

Amongst various futuristic renewable energy sources, hydrogen fuel is deemed to be clean and sustainable. Electrochemical water splitting (EWS) is an advanced technology to produce pure hydrogen in a cost‐efficient manner. The electrocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are the vital steps of EWS and have been at the forefront of research over the past decades. The low‐cost nanostructured metal phosphide (MP)‐based electrocatalysts exhibit unconventional physicochemical properties and offer very high turnover frequency (TOF), low over potential, high mass activity with improved efficiency, and long‐term stability. Therefore, they are deemed to be potential electrocatalysts to meet practical challenges for supporting the future hydrogen economy. This review discusses the recent research progress in nanostructured MP‐based catalysts with an emphasis given on in‐depth understanding of catalytic activity and innovative synthetic strategies for MP‐based catalysts through combined experimental (in situ/operando techniques) and theoretical investigations. Finally, the challenges, critical issues, and future outlook in the field of MP‐based catalysts for water electrolysis are addressed.

MOF-derived nanoarrays as advanced electrocatalysts for water splitting

“…In addition to metal oxides and hydroxides, MOFs can also be used as templates for fabricating sulfides and phosphides with complex nanostructures, which have been rapidly developed for electrocatalytic water splitting. 26,61,[119][120][121] The S and P atoms with high electronegativity would withdraw electrons from the metal centers, and the negatively charged S and P atoms are inclined to trapping the positively charged proton like a base. This can adjust the ability of the attachment and detachment of the H atoms of active sites for the HER.…”

Elaboration of Ni2P@C Composites with Hollow Porous Structure for Enhanced Overall Water Splitting

“…The Tafel slope of Ni 2 P@C-350 electrode falls in 40-120 mV dec -1 , indicating the corresponding HER reactions follow the Volmer-Heyrovsky mechanism (H 2 O + e -→ OH -+ H ads , H 2 O + e -+ H ads → OH -+ H 2 ) and the electrochemical recombination serves as the rate-determining step. [42,43] Electrochemical impedance spectroscopy (EIS) is employed to further investigate the conductivity and the mass transport rates of the catalysts. As illustrated in Figure 5c, Nyquist plots indicate that Ni 2 P@C-350 has the smallest semicircle diameter in high-frequency region, which has a charge transfer resistance (R ct ) of 6.74 Ω, meaning that Ni 2 P@C-350 possess the most rapid charge transport rate in electrochemical reaction.…”

Plant polyphenol-involved coordination assembly-derived Mo3Co3C/Mo2C/Co@NC with phase regulation and interface engineering for efficient hydrogen evolution reaction electrocatalysis

“…[8][9][10][11] Therefore, more efficient and stable non-precious metal-based materials with a low manufacturing cost are highly desired. Up to now, researchers have explored a variety of transition metalbased electrocatalysts, such as phosphides, [12][13][14] sulfides, [15][16][17][18] nitrides, 19,20 hydroxides [21][22][23] and selenides. [24][25][26] Transition metal carbides (TMCs) have attracted considerable interest as alternative catalysts to replace precious metals in the HER.…”

“…8–11 Therefore, more efficient and stable non-precious metal-based materials with a low manufacturing cost are highly desired. Up to now, researchers have explored a variety of transition metal-based electrocatalysts, such as phosphides, 12–14 sulfides, 15–18 nitrides, 19,20 hydroxides 21–23 and selenides. 24–26…”