development of noble metal-free cocatalysts with high efficiency, abundant storage,
and low cost are highly required.
Recently, transition metal phosphides (TMPs) have been widely studied as
typical representatives of burgeoning noble metal-free cocatalysts due to their
intriguing properties, such as approximate zero-valent metallic feature, high stability, low-cost, and highly capturing electron ability [31, 32]. In this chapter, we will
give a short overview of the recent research progress of transition metal phosphides
acted as cocatalysts in photocatalytic hydrogen evolution reactions. The preparation
methods, effects of P element, and photocatalytic applications of TMPs are comprehensively discussed.
16.2 Preparation Methods
As the first TMP, Ni 2 P was prepared for the application of vapor phase catalysis in
the 1950s [33]; it has been gradually depleted for half a century. With the development of synthetic and characteristic techniques, these TMPs materials have been
flourished as efficient earth-abundant cocatalysts in photocatalysis. In this section,
the synthesis strategies of TMPs will be categorized.
16.2.1 Organophosphorus Sources
Currently, there are two main preparation methods to synthesize TMPs. One is
realized in the presence of organophosphorus precursors. The other is to use
organophosphorus sources to obtain TMPs. In the latter method, tri-noctylphosphine (TOP), trioctylphosphine oxide (TOPO), and their analogue tris
(trimethylsilyl)phosphine (TMSP) and triphenylphosphine (TPP) are common and
attractive phosphorus sources in the synthesis of TMPs [34, 35].
Richard A. Jones and his coworkers [36] used ruthenium phosphite hydride
complexes H 2 Ru(P(OR) 3 ) 4 (R ¼ Me (1), Et (2),
i
Pr (3)) as the chemical vapor
deposition (CVD) precursors to deposit the films of amorphous ruthenium–phosphorus alloys. The crystal structure of as-prepared sample cis-H 2 Ru(P(OMe) 3 ) 4 ,
cis-H 2 Ru(P(OEt) 3 ) 4 , and Cl 2 Ru(P(OMe) 3 ) 4 is demonstrated in Fig. 16.2a–c. In the
structure of these complexes, the two P atoms of the mutually link phosphite ligands
at Ru, while the other two P(OMe) 3 ligands leave room for the coordination of the
relatively small hydride ligands. The synthetic strategies of ruthenium-P(OEt) ligand
complex are similar to that of these three complexes by using triethylphosphite as the
phosphorus containing ligand. For the single metal/phosphorus organic precursors,
the films of RuP are achieved via the chemical process by which both the Ru and P
attain a zero oxidation state upon deposition. It is noted that the thermal CVD
decomposition of organic phosphorus source to form TMPs shows more potential
in controlling the P concentration in TMPs than the phosphidation pathway.
16.2 Preparation Methods
377
and low cost are highly required.
Recently, transition metal phosphides (TMPs) have been widely studied as
typical representatives of burgeoning noble metal-free cocatalysts due to their
intriguing properties, such as approximate zero-valent metallic feature, high stability, low-cost, and highly capturing electron ability [31, 32]. In this chapter, we will
give a short overview of the recent research progress of transition metal phosphides
acted as cocatalysts in photocatalytic hydrogen evolution reactions. The preparation
methods, effects of P element, and photocatalytic applications of TMPs are comprehensively discussed.
16.2 Preparation Methods
As the first TMP, Ni 2 P was prepared for the application of vapor phase catalysis in
the 1950s [33]; it has been gradually depleted for half a century. With the development of synthetic and characteristic techniques, these TMPs materials have been
flourished as efficient earth-abundant cocatalysts in photocatalysis. In this section,
the synthesis strategies of TMPs will be categorized.
16.2.1 Organophosphorus Sources
Currently, there are two main preparation methods to synthesize TMPs. One is
realized in the presence of organophosphorus precursors. The other is to use
organophosphorus sources to obtain TMPs. In the latter method, tri-noctylphosphine (TOP), trioctylphosphine oxide (TOPO), and their analogue tris
(trimethylsilyl)phosphine (TMSP) and triphenylphosphine (TPP) are common and
attractive phosphorus sources in the synthesis of TMPs [34, 35].
Richard A. Jones and his coworkers [36] used ruthenium phosphite hydride
complexes H 2 Ru(P(OR) 3 ) 4 (R ¼ Me (1), Et (2),
i
Pr (3)) as the chemical vapor
deposition (CVD) precursors to deposit the films of amorphous ruthenium–phosphorus alloys. The crystal structure of as-prepared sample cis-H 2 Ru(P(OMe) 3 ) 4 ,
cis-H 2 Ru(P(OEt) 3 ) 4 , and Cl 2 Ru(P(OMe) 3 ) 4 is demonstrated in Fig. 16.2a–c. In the
structure of these complexes, the two P atoms of the mutually link phosphite ligands
at Ru, while the other two P(OMe) 3 ligands leave room for the coordination of the
relatively small hydride ligands. The synthetic strategies of ruthenium-P(OEt) ligand
complex are similar to that of these three complexes by using triethylphosphite as the
phosphorus containing ligand. For the single metal/phosphorus organic precursors,
the films of RuP are achieved via the chemical process by which both the Ru and P
attain a zero oxidation state upon deposition. It is noted that the thermal CVD
decomposition of organic phosphorus source to form TMPs shows more potential
in controlling the P concentration in TMPs than the phosphidation pathway.
16.2 Preparation Methods
377