Recent advances in non-metals-doped TiO2 nanostructured photocatalysts for visible-light driven hydrogen production,CO2 reduction and air purification

The generation of hydrogen and oxygen from the photocatalytic water splitting reaction under visible light is a promisingly renewable and clean source for H₂ fuel. The transition metal oxide semiconductors (e.g. TiO₂, WO_3, ZnO, and ZrO₂) are have been widely used as photocatalysts for the hydrogen generation. Because of safety, low cost, chemical inertness, photostability and other characteristics (bandgap, corrosion resistance, thermal and environmental stability), TiO₂ is considered as a most potential catalyst of the semiconductors being investigated and developed. However, the extensive applications of TiO₂ are hampered by its inability to exploit the solar energy of visible region. Other demerits are lesser absorbance under visible light, and recombination of photogenerated electron-hole pairs. In this review, we focus on the all the possible reactions taking place at the catalyst during photo-induced H₂ from water splitting reaction, which is green and promising technology. Various parameter affecting the photocatalytic water splitting reactions are also studied. Predominantly, this review is focussed on bandgap engineering of TiO₂ such as the upward shift of valence band and downward shift of conduction bands by doping process to extend its light absorption property into the visible region. Furthermore, the recent advances in this direction including various new strategies of synthesis, multiple doping, hetero-junction, functionalization, perspective and future opportunities of non-metals-doped TiO₂-based nanostructured photocatalysts for various photocatalytic applications such as efficient hydrogen production, air purification and CO₂ reduction to valuable chemicals have been discussed.     

Band gap engineering in huge-gap semiconductor SrZrO3 for visible-light photocatalysis

Using SrZrO₃ (SZO, the intrinsic band gap being 5.6 eV) as an example, we have investigated the design principles for huge-gap semiconductors with band gap larger than 5 eV for the application of efficient visible-light driven photocatalysts for splitting water into hydrogen. Based on the hybrid density function calculations, the electronic structures of mono-doped and co-doped SZO are investigated to obtain design principles for improving their photocatalytic activity in hydrogen generation. The cationic–anionic co-doping in SZO could reduce the band gap significantly and its electronic band position is excellent for the visible-light photocatalysis. This work reports a new type of candidate material for visible-light driven photocatalysis, i.e., huge-gap semiconductors with band gap larger than 5 eV. Furthermore, based on the present results we have proposed the design principles for band gap engineering that provides general guideline for other huge-gap semiconductors.     

Design and synthesis of Ti-peroxo/phosphorus heterostructures for enhanced photocatalytic hydrogen evolution

For the heterojunction composite photocatalyst, the contact interface is the key to charge carrier separation conditions. In order to present novel research through the interaction between these interfaces, the Ti based peroxo complex (TP)/red phosphorus (RP) composite system was introduced and designed to improve carrier separation and transport properties during photocatalytic hydrogen evolution. In this study, we have successfully synthesized TP/RP by facile solution process through stirring at room temperature and pressure. Regarding the specific surface area, which is one of the important factors in the photocatalytic activity, it was confirmed that the specific surface area of the TP (166.4 m²/g) and TP/RP (281.4 m²/g) samples was dramatically improved as the particle surface was oxidized based on TiH₂ (0.613 m²/g), the precursor. And the photo-induced charge carrier life time of the TP/RP was extended by approximately 60% compared to the conventional TP. Finally, excellent research results were obtained in which the photocatalytic hydrogen evolution efficiency (17.05 μmol/h) under visible-light irradiation (200 W Xenon lamp) was improved by about 3 times than that of the conventional TP sample (5.26 μmol/h).     

Solar photocatalysis, photodegradation of a commercial detergent in aqueous TiO2 dispersions under sunlight irradiation

A commercial detergent whose major components are an anionic surfactant and a fluorescent whitening agent can be photodegraded in aqueous TiO₂ dispersions under irradiation with concentrated sunlight in the presence of air. The degradation process followed apparent first-order kinetics in terms of the total sunlight energy impinging on the photoreactive system. The effects of (a) TiO₂ loading, (b) circulation flow rate, and (c) pH of the reactant solution on the kinetics of decomposition of the detergent were examined. Under the prevailing conditions, the optimal operational parameters for this detergent were, respectively: TiO₂ loading, 6 g l⁻¹; circulation flow rate, 4.9 l min⁻¹; and pH, 4.9. The rate of increase of the surface tension was greater than the rate of decrease of the concentration of the detergent. This study adds to our knowledge base in the effective use of sunlight irradiation to detoxify wastewaters containing undesirable detergents.     

Photocatalytic performance of S doped TiO2 in relation to processing conditions: calcination temperature and heating rate

Abstract

The effect of different heating profiles on the photocatalytic performance of sulphur doped TiO₂ photocatalysts is reported. The photocatalysts were synthesised by a sol–gel method using thiourea as the dopant precursor and characterised using X-ray diffraction, elemental analysis and reflection measurements. The degradation of dichloroacetic acid, under indirect sunlight and visible light irradiation, was used to determine the photocatalytic performance of the synthesised materials. A number of different commercial photocatalysts were used as comparative standards. In all the studied specimens, anatase TiO₂ was the dominant crystalline type. Additionally, compared with undoped TiO₂ and commercial standards, significant absorption into the visible region (400–470 nm) was observed for the modified TiO₂.     

Pd loading,Mn+ (n=1, 2, 3) metal ions doped TiO2 nanosheets for enhanced photocatalytic H2 production and reaction mechanism

Pd nanoparticles (NPs) loading, main group metal ions doped TiO₂ nanosheets were prepared by a hydrothermal method, followed by photo-deposition of Pd. The samples were characterized, and their photocatalytic hydrogen production activities were tested in a methanol aqueous solution. The effects of cationic charge, radius and concentration of the doping ions (Na⁺, K⁺, Mg²⁺, Al³⁺) on the photocatalytic activities were investigated systematically. The photocatalytic reaction mechanism was discussed by considering the three aspects: specific surface area, light absorption and charge transfer/separation. The results show that the cation dopings significantly increased the photocatalytic activities of the TiO₂ nanosheets, which may be attributed to the enhanced UV-vis light absorption and accelerated charge transfer/separation of the catalysts. Particularly, the Pd/0.2%K⁺-TiO₂ possesses the highest photocatalytic H₂ production activity (76.6 μmol h^?1), which is more than twofold higher than that of the undoped Pd/TiO₂. The apparent quantum efficiency of hydrogen evolution system reaches 3.0% at 365 nm. The high activity of the Pd/K⁺-TiO₂ may be attributed to the lower electronegativity of K⁺, caused by the lower cationic charge or the larger cationic radius, compared to Na⁺, Mg²⁺ and Al³⁺. The doping metal cations with higher electronegativity may compete electrons with H⁺, which eventually partly depressed the reduction of H⁺ to H₂.     

Recent progress in MoS2 for solar energy conversion applications

In an era of graphene-based nanomaterials as the most widely studied two-dimensional (2D) materials for enhanced performance of devices and systems in solar energy conversion applications, molybdenum disulfide (MoS₂) stands out as a promising alternative 2D material with excellent properties. This review first examined various methods for MoS₂ synthesis. It, then, summarized the unique structure and properties of MoS₂ nanosheets. Finally, it presented the latest advances in the use of MoS₂ nanosheets for important solar energy applications, including solar thermal water purification, photocatalytic process, and photoelectrocatalytic process.     

Nickel-doped TiO2 and thiophene-naphthalenediimide copolymer based inorganic/organic nano-heterostructure for the enhanced photoelectrochemical urea oxidation reaction

To overcome the global challenges of energy crises and environmental threats, urea oxidation is a hopeful route to utilize urea-rich wastewater as an energy source for hydrogen production. Herein, we report an inorganic/organic type of nano-heterostructure (NHs–Ni-TiO₂/p-NDIHBT) as a photoanode with excellent urea oxidation efficiency driven by visible light. This heterostructured photoanode consists of nickel (Ni)-doped TiO₂ nanorods (NRs) arrays as an inorganic part and a D-A-D type organic polymer i.e p-NDIHBT as an organic part. The as-prepared photoanode was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The morphological studies of TEM confirm the coating of p-NDIHBT on Ni–TiO₂ NPs (～1 μm). The consequence of heterostructure formation on optical and photoelectrochemical (PEC) properties of photoanode were explored through photoelectrochemical responses under visible light irradiation. The photoelectrochemical activity of Ni–TiO₂ and Ni–TiO₂/p-NDIHBT photoanode from linear sweep voltammetry (LSV) shows the ultrahigh photocurrent density of 0.36 mA/cm² and 2.21 mA/cm², respectively measured at 1.965 V_RHE. Electrochemical impedance spectroscopy (EIS) of both photoanodes shows a highly sensitive nature toward the urea oxidation reaction. The hybrid photoanode also exhibits high photostability, good solar-to-hydrogen conversion efficiency, and high faradaic efficiency for urea oxidation.     

Synergistic effects of advanced oxidization reactions in a combination of TiO2 photocatalysis for hydrogen production and wastewater treatment applications

In this paper, the synergistic effects of advanced oxidization reactions in a combination of TiO₂ photocatalysis are comparatively investigated for hydrogen production and wastewater treatment applications. An experimental study is conducted with a photoelectrochemical reactor under a UV-light source. TiO₂ is selected as the photocatalyst due to the high corrosion resistant nature and ability to form hydroxyl radicals with the interaction with photons. The synergetic effects of advanced oxidization processes (AOPs) such as Fenton, Fenton-like, photocatalysis (TiO₂/UV) and UV photolysis (H₂O₂/UV) are investigated individually and in a combination of each other. The Fenton type reagent in the reactor is formed by anodic sacrificial of stainless-steel electrode with the presence of H₂O₂. The influences of various parameters, including pH level, type of the electrode and electrolyte and the UV light, on the performance of the combined system are also investigated experimentally. The highest chemical oxygen demand (COD) removal efficiency is observed as 97.9% for the experimental condition which combines UV/TiO₂, UV/H₂O₂ and photo-electro Fenton type processes. The maximum hydrogen production rate from the photoelectrolysis of wastewater is obtained as 7.0 mg/Wh for the experimental condition which has the highest rate of photo-electro Fenton type processes. The average enhancement with the presence of UV light on hydrogen production rates and COD removal efficiencies are further calculated to be 3% and 20%, respectively.     

Pt modified TiO2/NiO p-n junction with enhanced surface reaction and charge separation for efficient photocatalytic hydrogen evolution

Efficient charge separation is crucial for solar energy conversion in semiconductor-based systems. Creating p-n junction is an effective strategy to enhance charge separation because the built-in electric field could inhibit charge recombination. However, in many situations, the high reaction barrier will limit the surface reaction rate, resulting in poor carrier utilization of the p-n junction. Here, with carefully designed cocatalyst loading, we successfully overcome the limitation and obtain the full effectiveness of the p-n junction. When used for photocatalytic water splitting, the well-designed catalyst exhibits excellent photocatalytic activity, with a hydrogen evolution rate as high as 13.2 mmol h^?1 g^?1, which is 18 times higher than that of the pristine p-n junction. Further investigation reveals that the enhancement should be attributed to the synergistic effect between cocatalyst and p-n junction, with the cocatalyst improves reaction rate on the surface and the p-n junction accelerates charge separation in the bulk simultaneously. This work provides an effective strategy to modify the surface properties of p-n junction through cocatalysts-loading for efficient photocatalytic hydrogen evolution.     

Load and weather profile,and time simulation impacts for the PEPITE PV/H2 project

This paper concerns the impacts of the meteorological data, the choice of the load profile, and the time simulation (1–11 years) on the energy flows and on the H₂/O₂/H₂O storage sizing in a photovoltaic/fuel cell/electrolyzer hybrid system (PEPITE project). The simulations were computed with the ORIENTE software. 4 load profiles have been investigated (3 diurnal and one nocturnal) with an identical daily consumption (26 kWh).     

Performance of Square and Trapezoidal photoreactors for solar hydrogen recovery from various industrial sulphide wastewater using CNT/Ce3+ doped TiO2

CNT/Ce³⁺ doped TiO₂ powder was synthesized using a sol-gel method and characterized by X-ray Diffraction, UV–vis Diffuse Reflectance Spectroscopy, FTIR, EDX, Raman, Transmission Electron Microscopy (TEM), BET and PL. Direct sunlight illumination was used to check the photocatalytic activity of CNT/Ce³⁺ doped TiO₂ for hydrogen production from sulphide wastewater. Sulphide wastewater collected from various industries viz., STP (Sewage Treatment Plant), Refinery (Amine solution) and Tannery (soak pit) were used to test the photocatalytic hydrogen recovery. The suitable industrial wastewater which generates maximum hydrogen was used to check the effect of various operating parameters viz., sulphide ion concentrations, sulphite ion concentrations and catalyst dosage. The maximum hydrogen recovery achieved was found to be 14,500 μmol/h.     

Light-induced confined growth of amorphous Co doped MoSx nanodots on TiO2 nanoparticles for efficient and stable in situ photocatalytic H2 evolution

Amorphous molybdenum sulfide (a-MoS_x) prepared by in situ photoreduction method with an abundance of exposed active sites has been identified as an efficient cocatalyst for catalyzing photocatalytic H₂ evolution reaction (HER). However, the intrinsic activity of the a-MoS_x cocatalyst toward HER is low due to the unfavorable electronic structures of the active sites. Herein, we report a facile light-induced method for the confined growth of transition metal (TM) doped MoS_x (a-TM-MoS_x) cocatalysts on TiO₂ nanoparticles and their catalytic activity for in situ photocatalytic HER. It is found that doping Co into a-MoS_x can greatly enhance the activity of resulted a-Co-MoS_x cocatalyst for photocatalytic H₂ evolution over TiO₂ among the transition metal dopants (Co, Ni, Fe, Cu, Zn) tested. The most efficient a-Co-MoS_x cocatalyst (Co/Mo = 1/4 and 4 mol% loading) loaded TiO₂ (TiO₂/a-Co-MoS_x) shows a H₂ evolution rate of 133.8 μmol h⁻¹, which is 3.3 times higher than that of a-MoS_x loaded TiO₂ (TiO₂/a-MoS_x). Moreover, the TiO₂/a-Co-MoS_x photocatalyst shows excellent recycling H₂ evolution stability. The characterization results reveal that a-Co-MoS_x cocatalyst can not only effectively capture the photogenerated electrons of TiO₂ to greatly enhance the separation efficiency of photogenerated charges but also significantly reduce the overpotential of HER due to the formation of highly active “CoMoS” sites, thus synergistically enhancing the catalytic activity of TiO₂/a-Co-MoS_x. Moreover, the light-induced growth of a-Co-MoS_x on TiO₂ is found to readily couple with the in situ photocatalytic HER. Therefore, this work provides a simple and efficient strategy for designing high-performance a-MoS_x-based cocatalysts for stable in situ photocatalytic H₂ evolution.     

Effect of hydrocarbon fractions,N2 and CO2 in feed gas on hydrogen production using sorption enhanced steam reforming: Thermodynamic analysis

H₂ yield and purity from sorption enhanced steam reforming (SE-SR) are determined by temperature, S:C ratio in use, and feed gas composition in hydrocarbons, N₂ and CO₂. Gases with high hydrocarbons composition had the highest H₂ yield and purity. The magnitude of sorption enhancement effects compared to conventional steam reforming (C-SR), i.e. increases in H₂ yield and purity, and drop in CH₄ yield were remarkably insensitive to alkane (C1C3) and CO₂ content (0.1–10 vol%), with only N₂ content (0.4–70 vol%) having a minor effect. Although the presence of inert (N₂) decreases the partial pressure of the reactants which is beneficial in steam reforming, high inert contents increase the energetic cost of operating the reforming plants. The aim of the study is to investigate and demonstrate the effect of actual shale gas composition in the SE-SR process, with varied hydrocarbon fractions, CO₂ and N₂ in the feedstock.     

Fabrication of rGO/CdS@2H, 1T,amorphous MoS2 heterostructure for enhanced photocatalytic and electrocatalytic activity

The synthesis of high efficiency noble metal free catalysts is an important target for H₂ production by water-splitting. In this work, rGO/CdS@MoS₂ heterostructure with two catalytic paths was successfully synthesized and as the first applied the heterostructure in the field of electrocatalysis. The MoS₂ structure is adjusted by controlling hydrothermal process. Moreover, the effects of structure and loading amount of 2H–MoS₂, 1T-MoS₂ and amorphous MoS₂ (A-MoS₂) on catalytic performance were also studied. The catalytic activity of rGO/CdS@MoS₂ heterostructure has been improved obviously. Compared with 2H–MoS₂, the distortion of 1T-MoS₂ and the defect of A-MoS₂ make it have more unsaturated S, so rGO/CdS@1T-MoS₂ and rGO/CdS@A-MoS₂ have better catalytic activity. For photocatalytic H₂ evolution, loading MoS₂ and rGO on catalysts changes the energy band structure, promotes the separation of electron-holes and provides a large number of active sites. Among them, the visible light photocatalytic H₂ production rate of rGO/CdS@1T-MoS₂ with 0.1 mol of 1T-MoS₂ (CT0.1-G1) is 18.26 mmol/g/h. During the electrocatalytic H₂ evolution, introducing MoS₂ and rGO improves electronic structure and increases active sites. rGO/CdS@1T-MoS₂ with 0.5 mol of 1T-MoS₂ (CT0.5-G1) shows the low overpotential (312 mV) and Tafel slopes (85 mV/dec).     

Rare earth metal Gd influenced defect sites in N doped TiO2: Defect mediated improved charge transfer for enhanced photocatalytic hydrogen production

In this experimental studies, we report the synthesis of TiO₂ co-doped by both cationic and anionic sites by simple sol-gel based method. All the prepared samples exhibit the anatase crystalline morphology however, showed lattice distortion caused by the displacement of Ti⁴⁺ sites by Gd³⁺. The improved visible absorption is witnessed by the Gd and N co-doping with an assured redshift in the absorption edge. The N and Gd displacement inside TiO₂ lattice accompanied by the creation of OTiN and GdOTi bonds are characterized by the X-ray photoelectron spectra. The strong resonance signal by Gd4f electrons in the electron paramagnetic resonance spectroscopy further substantiate the displacement of lattice cites of TiO₂ by Gd³⁺ ions. The longevity of the photo produced charges observed in fluorescence spectra of Gd and N co-doped TiO₂ is because of the effective transfer of charges to the defect sites. The aforementioned catalysts are tested for their capacity for the H₂ production from water splitting. The 2 wt% gadolinium and nitrogen co-doped TiO₂ has shown 10764 μmol g^?1 H₂ production which is 26 times higher than the commercial Degussa P-25 catalyst. The enhanced activity for hydrogen production can be attributed to factors such as increased absorptivity under visible light and effective charge carrier separation.     

Preparation of TiO2 nanofibers,porous nanotubes,RGO/TiO2 composite by electrospinning and hydrothermal synthesis and their applications in improving the electrochemical hydrogen storage properties of Co2B material

Co₂B hydrogen storage material was prepared via a high temperature solid phase process. The TiO₂ nanofibers (TiO₂–NF) and TiO₂ porous nanotubes (TiO₂-NT) with different size, structure and morphology were fabricated by electrospinning and hydrothermal synthesis. In order to improve the conductivity, the reduced graphene oxide/TiO₂ nanotubes composite (RGO/TiO₂-NT) was synthesized by an alkaline hydrothermal process. The three-dimensional porous TiO₂ nanotubes were attached to the two-dimensional RGO and formed a uniform dispersion. For the purpose of improving the electrochemical performance of Co₂B, composites of Co₂B doped with TiO₂–NF, TiO₂-NT and RGO/TiO₂-NT were manufactured by ball milling. Ultimately, all the composite electrodes showed higher discharge capacities than ordinary Co₂B. Among them, Co₂B modified with RGO/TiO₂-NT exhibited the highest discharge capacity (691.4 mAh/g). TiO₂-NT with large specific surface area and unique tubular porous structure can offer sufficient electrochemical active sites to anchor hydrogen and improve the electrocatalytic activity of Co₂B, meanwhile, the RGO component in RGO/TiO₂-NT with excellent electrical conduction can further provide fast channels for charger transfer during the charging/discharging processes. Moreover, the corrosion resistance, HRD and kinetics performance of Co₂B were also enhanced after doping of TiO₂–NF, TiO₂-NT and RGO/TiO₂-NT.     

Reactivity of Ni,Cr and Zr doped ceria in CO2 splitting for CO production via two-step thermochemical cycle

This work focuses on modification and screening of ceria-based oxides for solar H₂O/CO₂ splitting via two-step thermochemical cycle. Ce_1-xM_xO_2-δ (M = Zr, Ni, Cr; x = 0, 0.05, 0.10, 0.15, 0.20) were synthesized via sol-gel method and tested for CO₂-splitting via two-step thermochemical cycles. Reduction was conducted at 1500 °C through a ramp rate of 10 °C/min and oxidation was performed at 1000 °C isothermally. Both Ni and Cr showed low solubility in ceria and no or very limited promoting effect on CO productivity. Cr could be reduced in the first reduction step but cannot be oxidized by CO₂ in the following oxidation step. Zr doped sample showed advantages in both CO productivity and lattice stability. 15% Zr doped exhibited the best performance with the CO productivity of 315.40 μmol/g. However, the oxidation rate of Zr doped samples was much lower than that of pure ceria. Compromise between fuel productivity and fast kinetics should be made in practical application.     

Rare earth (Sm/Eu/Tm) doped ZrO2 driven electro-catalysis,energy storage,and scaffolding in high-performance perovskite solar cells

Current work presents the first report on the modification of zirconia (ZrO₂) by doping it with the lanthanides oxides i.e. [samarium, europium, and thulium] forming a [Sm/Eu/Tm] co-doped ZrO₂ system. Lanthanide doping tailored the structure of host material by causing considerable bandgap energy shrinkage from 4.04 to 3.57 eV and reduction in the crystallite size from 67.92 to 45.23 nm. Profound electro-catalytic potential was reflected analyzed via linear sweep voltammetry showing the excellent of developed catalytic towards H₂ evolution with lower overpotential i.e. 133 mV and Tafel slope of 119.3 mV dec⁻¹. While for O₂ evolution, the electro-catalyst succeeded in gaining overpotential and Tafel slope values of 310 mV and 294.8 mV dec⁻¹, respectively. With such values, this material has surpassed the conventional electro-catalysts and is proved to be an excellent hydrogen producing electro-catalyst. The electrical charge storage potential was analyzed for [Sm/Eu/Tm] co-doped ZrO₂ decorated nickel foam electrode for development into a super-capacitor. This electrode was impressively stable for 10 cycles after 20 days checked through cyclic voltammetry. Furthermore, an augmented specific capacitance of 447 F g⁻¹ was achieved by the doped electrode when compared with the pristine one approaching 83.69 F g⁻¹. The electrical energy storage capacity of [Sm/Eu/Tm] co-doped ZrO₂ is even higher than the conventionally used metal oxides. In terms of the interfacial electrode-electrolyte, electrochemical impedance spectroscopy was done expressing the excellent ionic diffusion and electrochemically active sites for [Sm/Eu/Tm] co-doped ZrO₂ electrode with minimal resistance. The developed doped system was used a spacer layer in a cesium lead halide perovskite solar cells having planar architecture. The spacer layer containing solar cell device succeeded in gaining a power conversion efficiency of 16.31% and a fill factor of 78% evaluated via photo-current measurements carried out under artificial solar irradiance. The impressively higher fill factor shows the effective passivation and scaffolding by the [Sm/Eu/Tm] co-doped ZrO₂. The associated device was also marked by negligible hysteresis. Chrono-potentiometry and chrono-amperometry expressed commendable accelerated service lives for 100 min inside an electrolyte. The lanthanide co-doped ZrO₂ is an effective material for the utilization in energy systems associated with the electro-catalysis of water, charge storage electrode for super-capacitors, and photovoltaic solar to electrical energy conversion.     

Synthesis,characterization and catalytic study of Sm doped LaNiO3 nanoparticles in reforming of methane with CO2 and O2

A series of Sm doped LaNiO₃ nanoparticles by solids denoted as La_1−xSm_xNiO_3−δ (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1) were synthesized by the modified citrate sol–gel method. The prepared compounds were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), BET specific surface area and scanning and transmission electron microscopy (SEM–TEM) techniques. The results showed that highly homogeneous and crystalline oxides with particle sizes in the range of nanometers were obtained through this synthesis method. The XRD patterns of the prepared La_1−xSm_xNiO_3−δ solids confirmed the perovskite structure for the samples up to x = 0.1. When the degree (x > 0.1) of substitution increase the formation of spinel-type La₂NiO₄ and mixed NiO, Sm₂O₃ phases are favored thermodynamically and the rate of perovskite structure formation decreased drastically. The effects of the partial substitution of La by Sm, reaction temperatures and feed gas ratio at atmospheric pressure were investigated in process of combined carbon dioxide reforming and partial oxidation of methane (CDRPOM), after reduction of the samples under hydrogen. All samples presented similar activity at 1073 K while at lower temperatures, the La_1−xSm_xNiO_3−δ catalysts with x = 0, 0.1, 0.9 and 1 showed the highest activity.