TABLE 3.

Photocatalytic CO₂ reduction performance on typical TiO₂-based S-S (Z-scheme), S-M, S-C, multicomponent, phase and facet heterojunctions.

Photocatalyst	Reductant	Light source	Generation rate of main products (μmol∙gcat −1∙h−1)	Quantum efficiency (%)	References
Indirect Z-scheme heterojunction
CdS/rGO/TiO2	H2O vapor	300 W	CH4: 0.12 (μmol∙h−1)	-	Kuai et al. (2015)
		Xe lamp
CuGaS2-RGO-TiO2	Na2S aqueous solution	300 W	CO: 0.15	-	Takayama et al. (2017)
		Xe lamp (λ > 330 nm)	H2: 28.8 (μmol∙h−1)
Al−O Linked porous-g-C3N4/TiO2-nanotube (PCN/TNT)	Na2SO4 aqueous solution	150 W Xe lamp	CH3COOH	-	Wu et al. (2019)
			HCOOH
			CH3OH
ZnFe2O4/Ag/TiO2 nanorods	H2O vapor	200 W Hg lamp	CO: 1025	-	Tahir (2020)
			CH4: 132
			CH3OH: 30.8
			C2H6: 19.1 (μmol∙h−1)
g-C3N4/Pt/3DOM-TiO2@C	H2O vapor	300 W Xe lamp (λ ≥ 420 nm)	CO: 1.47	5.67	Wang et al. (2020a)
			CH4: 6.56
			H2: 0.82
(Au/A-TiO2)@g-C3N4	H2O vapor	300 W Xe lamp (λ ≥ 420 nm)	CH4: 37.4	1.91	Wang et al. (2020b)
			CO: 21.7
Direct Z-scheme heterojunction
Cu2O/TiO2	H2O vapor	1 kW high-pressure Hg (Xe) arc lamp (λ ≥ 305 nm)	CO: 2.11	-	Aguirre et al. (2017)
ZnIn2S4/TiO2	H2O vapor	300 W Xe lamp	CH4: 1.135	-	Yang et al. (2017)
TiO2/CuInS2	H2O vapor	350 W Xe lamp	CH4: 2.5	-	Xu et al. (2018b)
TiO2/CdS	H2O vapor	300 W Xe lamp	CH4: 11.9	-	Low et al. (2019)
			μmol∙h−1∙m−2
Zn3In2S6/TiO2	H2O vapor	300 W Xe lamp	CH4: 6.19	-	She et al. (2018)
			CO: 23.35
Nb-TiO2/g-C3N4	H2O vapor	Two 30 W white bulbs	CH4: 562	-	Thi Thanh Truc et al. (2019)
			CO: 420
			HCOOH: 698
Copper (II)-porphyrin zirconium metal-organic framework (PCN-224(Cu))/TiO2	Na2SO4 aqueous solution	300 W Xe lamp	CO: 37.21	-	Wang L. et al. (2019)
WO3-TiO2/Cu2ZnSnS4	H2O vapor	400 W Xe lamp (λ > 420 nm)	CH4: 1.69	0.52	Raza et al. (2020)
			CO: 15.37
Au-TiO2	H2O vapor	AM1.5 G simulated sunlight	CH4: 302	-	Zeng et al. (2020)
		50 W white cold LED light (λ > 400 nm)	HCHO: 420	-
			CO: 323
Single metal
3DOM Au/TiO2	H2O vapor	300 W Xe lamp	CH4: 2.89	-	Jiao et al. (2015)
Pt2+-Pt0/TiO2	H2O vapor	300 W Xe lamp	H2: 394.7	0.36	Xiong et al. (2015)
			CH4: 37.78
			CO: 8.03
Ag/TiO2	H2O vapor	300 W Xe lamp	CH4: 1.40	0.16 (400 nm); 0.013 (520 nm)	Yu et al. (2016)
Ag/TiO2 nanorod arrays	H2O vapor	300 W Xe lamp (λ > 420 nm)	CH4: 1.13	-	Cheng et al. (2017)
			CO: 12
Pt/TiO2	H2O vapor	Four 6 W lamps (λ ≤ 365 nm)	CH4	-	Tasbihi et al. (2018a)
Pt/TiO2-COK-12			CO
Ag/TiO2 nanotube arrays (TNTAs)	H2O vapor	300 W Xe lamp	CH4	-	Low et al. (2018)
Pt/TiO2-Al2O3 foam	H2O vapor	UV 8 W Hg lamp	H2: 22.5	-	Tasbihi et al. (2018b)
			CH4: 1.21
			CO: 0.54
Au-TiO2 Nanotubes (TNTs)	H2O vapor	300 W Xe lamp	CH4: 14.67%	-	Khatun et al. (2019)
Au/TiO2	H2O vapor	300 W Xe lamp	CH4: 70.34	-	Wang R. et al. (2019)
			CO: 19.75
Au/TiO2	H2O vapor	300 W Xe lamp	CH4: 0.2	-	Wang et al. (2021)
			CO: 1.2
Metal alloy
(Au, Cu)/TiO2	H2O vapor	AM1.5 G simulated sunlight	H2: 286	-	Neaţu et al. (2014)
			CH4: 2200 ± 300
AgPd/TiO2	Triethylamine (TEA) aqueous solution	300 W Xe lamp	H2: 144.5	-	Tan et al. (2018)
			CH4: 79.0
PtRu/TiO2	H2O vapor	300 W Xe lamp	H2: 16.5	0.98	Wei Y. et al. (2018)
			CH4: 38.7
			CO: 2.6
Hierarchical urchin-like yolk@shell TiO2-xHx (HUY@S-TOH)/AuPd	H2O (liquid)	300 W Xe lamp	CH4: 47.0	-	Ziarati et al. (2020)
Graphene and its derivatives
Graphene-TiO2	H2O vapor	300 W Xe lamp	CH4: 8	-	Tu et al. (2013)
			C2H6: 16.8
RGO/Pt-TiO2 nanotubes (TNTs)	H2O vapor	500 W tungsten-halog--en lamp	CH4: 10.96 (μmol∙m−2)	-	Sim et al. (2015)
TiO2/Nitrogen doped rGO (NrGO)	H2O vapor	400 W Xe lamp	CO: 50	0.0072	Lin et al. (2017)
GO/oxygen rich TiO2 (OTiO2)	H2O vapor	300 W Xe lamp	CH4: 0.43	0.0103	Tan et al. (2017)
rGO/TiO2	H2O vapor	500 W Hg lamp	CH4: 12.75	-	Shehzad et al. (2018a)
			CO: 11.93
((Pt/TiO2)@rGO)	H2O vapor	300 W Xe lamp	H2: 5.6	1.93	Zhao Y. et al. (2018)
			CH4: 41.3
			CO: 0.4
Graphene quantum dots (GQDs)/TiO2	H2O vapor	100 W Xe solar simulator	CH4: 1.98 (ppm∙cm−2∙h−1)	-	Zubair et al. (2018)
rGO/TiO2	Triethanolamine (TEOA) aqueous solution	8 W UV-A lamp	CH3OH: 2330	-	Olowoyo et al. (2019)
CNT
MWCNT/TiO2	H2O vapor	15 W UV lamp	CH4: 11.74	-	Xia et al. (2007)
			HCOOH: 18.67
			C2H5OH: 29.87
MWCNT/TiO2	H2O (liquid)	15 W energy saving light bulb	CH4: 0.17	-	Gui et al. (2014)
Ag-MWCNT@TiO2	H2O vapor	15 W energy saving light bulb	CH4: 0.91	-	Gui et al. (2015)
			C2H6: 0.048
MWCNT/TiO2	TEOA aqueous solution	8 W UV-A lamp	H2: 2360.0	-	Olowoyo et al. (2019)
			CH3OH: 3246.1
			HCOOH: 68.5
CNT/TiO2/Cu	H2O vapor	300 W Xe lamp	CH4: 1.1	-	Rodríguez et al. (2020)
			CO: 8.1
Other carbon forms
Carbon@TiO2 hollow spheres	H2O vapor	300 W Xe lamp	CH4: 4.2	-	Wang et al. (2017)
			CH3OH: 9.1
N, S-containing carbon quantum dots (NCQDs)/TiO2	H2O vapor	300 W Xe lamp	CH4: 0.13	-	Li et al. (2018)
			CO: 0.19
Carbon nanofibers@TiO2	H2O vapor	350 W Xe lamp	CH4: 13.52	-	Zhang J. et al. (2018)
MgO-Pt-TiO2	H2O vapor	100 W Xe lamp	H2: 14	-	Xie et al. (2014)
			CH4: 1.2
			CO: 1.8
Pt-rGO-TiO2	H2O vapor	15 W energy saving light bulb	CH4: 0.28	-	Tan et al. (2015)
Pd-rGO-TiO2			CH4: 0.20
Ag-rGO-TiO2			CH4: 0.17
Au-rGO-TiO2			CH4: 0.13
Pt-Cu2O/TiO2	H2O vapor	300 W Xe lamp	CH4: 1.42	-	Xiong et al. (2017c)
			CO: 0.05
WSe2-Graphene-TiO2	Na2SO3 aqueous solution	300 W Xe lamp	CH3OH: 6.33	-	Biswas et al. (2018)
Pt/MgAl layered double oxides (MgAl-LDO)/TiO2	H2O (liquid)	300 W Xe lamp	CH4: 1.42	-	Chong et al. (2018)
			CO: 2.3
TiO2-Graphene few-layered MoS2	H2O vapor	300 W Xe lamp	CO: 92.33	-	Jung et al. (2018)
Au/Al2O3/TiO2	H2O vapor	450 W Xe lamp	CO: 11.8	-	Zhao H. et al. (2018)
TiO2-MnOx-Pt	H2O vapor	350 W Xe lamp	CH4: 34.67	-	Meng et al. (2019)
			CH3OH: 30.33 (μmol∙m−2∙h−1)
Ag-MgO-TiO2	H2O vapor	300 W Xe lamp	CH4: 0.86	0.091	Xu et al. (2018a)
			CH3OH: 0.06
Au@TiO2 hollow spheres (THS)@CoO	H2O vapor	300 W Xe lamp	CH4: 13.3	-	Zhu et al. (2019)
Phase heterojunction
Anatase-rutile TiO2 fibers	H2O vapor	Four 6 W	CO: 10.19	0.036	Reñones et al. (2016)
		UV lamps	CH4: 1.34
			H2: 19.94
Anatase-rutile TiO2 nanoparticles with oxygen vacancy	H2O vapor	300 W	CH4: 43.2	-	Xiong et al. (2020)
		Xe lamp
Disordered Anatase/ordered rutile (Ad/Ro) TiO2 nanoparticles	H2O vapor	Solar simulator 1 Sun	CH4: 3.98	0.273	Hwang et al. (2019)
			CO: 3.02
Pt-loaded anatase-rutile TiO2 nanoparticles	H2O vapor	200 W Hg–Xe light	CH4	-	Lee et al. (2016)
			CO
N-doped carbon coating paragenetic anatase/rutile heterojunction	TEOA and MeCN	300 W	CO: 24.31	-	Chen et al. (2020)
		Xe lamp
SrCO3-Modified brookite/anatase TiO2 heterojunction	H2O vapor	300 W	CH4: 19.66	-	Jin et al. (2019)
		Xe lamp	CO: 2.64
Facet heterojunction
{101}/{001} TiO2	H2O vapor	300 W	CH4: 1.35	-	Yu et al. (2014)
		Xe lamp
Oxygen-deficient {101}/{001} TiO2	H2O vapor	100 W Hg lamp/450 W Xe lamp	CO: ∼10.91 (UV-vis)	0.31 (UV-vis)	Liu L. et al. (2016)
			CO: ∼5.36 (visible)	0.134 (visible)
Pt-loaded {101}/{001} TiO2	0.1 M KHCO3 solution	250 W Hg lamp	CH4: 4.0	-	Cao et al. (2016)
Pt-loaded {101}/{001} TiO2	H2O vapor	300 W	CH4: 4.6	-	Xiong et al. (2017a)
		Xe lamp	H2: 9.9
Graphene supported {101}/{001} TiO2	H2O vapor	300 W	CO: 70.8	CO: 0.0557 CH4: 0.0864	Xiong et al. (2016)
		Xe lamp	CH4: 27.4